Fur Seal Meets Penguin: The Hunter vs. The Hunted

Seasonally abundant populations of some organisms are important to the ecosystem in which they are seasonally abundant. If the populations are over-hunted or over-bred, the ecosystem will be put out of balance and begin to degrade. Such an example is the Adélie penguin and Chinstrap penguin. They are relatively common in Antarctic waters, but recent work shows the importance to ecosystems common species. If the species were to decline even a little, the function, services, and structure of the ecosystem could collapse. The authors of this paper observed several encounters between the penguins (usually juvenile fledglings) and Antarctic fur seals.

The authors knew that the seals have hunted penguins before because it was done in an efficient, effective manner, and it did not look as though it was the seals first time at hunting penguins. They observed that after the catch, the seals would shake the penguin, ripping chunks of flesh, skin, and feathers off, swallowing the chunks. The authors observed a seal eating a carcass, but could not ascertain whether or not the seal killed or scavenged it. The authors also observed various sea birds taking advantage of the seals expertise in acquiring a penguin, and one bird (a Giant Petrel) actually “stole” a penguin carcass from a fur seal. The bird and the seal both had a carcass and were observed to be eating the flesh or stomach contents of the bird. It is possible that these hunting events occur wherever the penguins and fur seals ranges overlap.

Figure 1. A subadult male fur seal grasping a fledgling Adelie penguin (Photo by INV)

The two types of penguins and the fur seals are all common species in the Antarctic, and they overlap quite profusely. It is unknown how or why the fur seals hunt the penguins. It is possible that they learned their technique from Giant Petrels or other species of seals, such as the Leopard Seal which is known to regularly hunt penguins. The authors think it is possible that the seals supplement their typical diet with penguins in an opportunistic manner. They also think that penguin predation is a more regular occurrence than previously recognized due to the high amount of penguin feathers in seal scat.

 When examining the scat of many different seals from several different islands, it was found that the seals diet was predominately penguin with some krill (due to the pink coloration). Species of penguin was undetermined. The high amount of predation is thought to be near the end of the season when fledgling chick’s numbers are high and adults are returning from hunting, thus having a full stomach. This may suggest that penguins are actually an important part of the seals diet, and not just an opportunistic meal. If the fledglings are targeted only in an opportunistic manner, long term effects will be minimal. However, if they are targeting adult penguins, the effect will hit both the adults and the chicks, decreasing populations sizes overall. This could affect penguin ecology in general. 

Although this entire paper was based off of a few observations of fur seals preying on penguins thus making it partially biased, it may also indicate an increase in fur seal predation on penguins that are seasonally abundant, and this could cause a long-term decline in penguin numbers if the seals and their preying ways continue to increase. This paper was designed in the hopes of encouraging other naturalists to document observations such as these. It would be of great value for scientists to conduct systematic observations at different locations to determine the scope of this predation in its entirety.

References 

Orca Research Trust - Scientific Articles

New Species of Lobsters Prompt Re-Analysis of Kiwaid Biogeographical History

Recently two new species of kiwaid squat lobsters were found on hydrothermal vents in the Pacific Ocean and in the Pacific sector of the Southern Ocean. Finding these two new species had prompted the re-analysis of the kiwaid bio-geographical history. These squat lobsters are commonly known as "Yeti crabs." The yeti crabs get most of their nutrition from chemosynthetic episymbiotic bacteria growing on setae on their ventral surface and appendages. All but one species of kiwaid have been collected from hydrothermal vents. The other species, Kiwa puravida, was collected from cold seeps on the Pacific continental slope near Costa Rica. All the species were found in the Pacific or the Pacific sector of the Southern Ocean; however one species, Kiwa tyleri, is found in mass amounts at vents on the East Scotia Ridge in the Atlantic sector of the Southern Ocean.

Figure 1: Photos of known Yeti crabs.
 A) Kiwa puravida B) Kiwa sp. Galapagos Microplate C) Kiwa araonae D) Kiwa hirsuta E) Kiwa tyleri (F) Kiwa sp. SWIR
Scale bars are an approximation and represent 10 mm.

The first new species to be discovered was found on hydrothermal vents on the Galapagos Microplate and is called Kiwa sp. GM. The Galapagos Microplate is a distinct spreading system between the Galapagos Rift and the northern and southern portions of the East Pacific Rise. The second species is known as Kiwa araonae. This species is found on vents on the Australian-Antarctic Ridge in the southwest Pacific sector of the Southern Ocean. The discovery of this species widens the original known range of the Yeti crabs by ~6,500 km. This discovery suggests that the spread of the Yeti crabs is more complicated than previously believed. This discovery also suggests that the original seep-to-vent evolutionary progression may be wrong.

Figure 2: Map showing locations of kiwaids and the Cretaceous stem lineage fossil Pristinaspina gelasina in relation to land-masses and mid-ocean ridges.
Kiwaid are: i) Kiwa puravida, ii) Kiwa sp. GM, iii) Kiwa hirsuta, iv) Kiwa araonae, v) Kiwa tyleri, vi) Kiwa sp. SWIR.
Abbreviations are: NEPR = Northern East Pacific Rise; SEPR = Southern East Pacific Rise; GR = Galapagos Rift; GM = Galapagos Microplate; PAR = Pacific-Antarctic Ridge; AAR = Australian-Antarctic Ridge; CR = Chile Rise; ESR = East Scotia Ridge; AmAR = American-Antarctic Ridge; SWIR = Southwest Indian Ridge; CIR = Central Indian Ridge; SEIR = Southeast Indian Ridge; MAR = Mid-Atlantic Ridge.

The researchers found through many tests that Kiwaidae most likely originated in the Pacific. The researchers also found that the pattern of divergence could be closely linked to the evolution and movement of mid-ocean spreading ridges supporting hydrothermal vent habitats. Kiwaids, minus the one species mentioned earlier, are found only at hydrothermal vents along with BEAST analysis indicates that the common ancestor most likely inhabited the vents. They found that in other vent-associated taxa appeared consistent with movement and evolution of active spreading ridges. While there are puzzling reasons to why there are Yeti crabs are in certain areas there is also puzzling questions to why they are not in other areas.

Figure 3: The present-day configuration of mid-ocean ridges in the tropical East Pacific and the location of all currently known kiwaids

Yeti crabs are expected to be in areas such as vents along both the Galapagos Rift and the southern EPR, however they are absent from these. These vents have been majorly explored and no kiwaids have been found in them to this day. This study was done to include the two newest species and add on to a report previously done that included the previous four species. The research recently done does support the earlier inference to East Pacific origin. The research also shows that the divergence estimates are broadly similar to previous studies. 

Source for paper and figures 1-3:
Roterman CN, Lee WK, Liu X, Lin R, Li X, et al. (2018) "A New Yeti Crab Phylogeny: Vent Origins with Indications of Regional Extinction in the East Pacific." PLOS ONE 13(3):e0194696

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0194696

Rising Carbon Levels Are Affecting Squid's Hunting Habits

Over the years the carbon level on Earth has raised by humans and the oceans absorb more than a quarter of excess carbon. The more carbon absorbed makes the water more acidic. Blake Spady from the ARC Centre of Excellence for Coral Reef Studies at James Cook University led an investigation to see how these increasing levels of carbon are effecting the behaviors of Cephalopods. Most studies prior to his were done with fish, however he chose Cephalopods because little was known on the affects of elevated carbon was on them. He researched the affects on two kinds of squid: the pygmy squid and the bigfin reef squid.

Figure 1: One of the two kinds of squid worked on the bigfin reef squid, Sepioteuthis Lessoniana 

They studied how the carbon levels were affecting how the behaved when catching their prey. They wanted to see how their hunting patterns were affected. They found that the same number of bigfin reef squid attacked their prey after being exposed to elevated carbon, however they were slowed down. They also found that the bigfin reef squid used different body patterns more often that the squid not exposed.

Figure 2: Pygmy squid, Idiosepius paradoxus

The pygmy squid was different from the bigfin reef squid. This time the researchers saw that the pygmy squid decreased in the amount they attacked. They found there was a 20% decrease in the proportion of pygmy squid that attacked their prey when exposed. They also saw that like the bigfin reef squid they were slower to attack their prey and changed body patterns more often. They also attacked their prey from farther away. Spady also found that both species showed increased activity when they were not hunting. He believes that they could be adversely altering their "energy budgets." Overall they found that the increased carbon had similar affects on the two squid species, suggesting that a variety of Cephalopods could be affected by the rising carbon levels in the oceans. This could cause massive problems in marine ecosystems. The next step in research is to determine how well these species and other marine species can adapt to the growing carbon in their environment. 

Source for article and figure 1: 

https://www.eurekalert.org/pub_releases/2018-03/acoe-hss032018.php

Source for figure 2:

https://alchetron.com/Idiosepius

Behavior of a Solitary Wild Bottlenose Dolphin

The bottlenose dolphin, Tursiops truncatus, is a widely popular marine mammal and the most common member of the family Delphinidae. The wild bottlenose dolphin can be found worldwide in tropical and temperate waters. They are commonly found in groups of 2 to 15 dolphins, although offshore herds are sometimes comprised of several hundred individuals. Bottlenose dolphins use echolocation to locate and capture prey, which consists of benthic invertebrates and fish for coastal individuals, and pelagic squid and fish for those offshore.

Figure 1. A small group of wild bottlenose dolphins

The presence of wild bottlenose dolphins in an area commonly generates strong public interest which can result in an increase in boat activity. This can potentially cause altered behavior and may pose a threat for the dolphins’ wellbeing. Several studies have been done on small groups of coastal bottlenose dolphins and have observed the dolphins spending more time underwater in order to avoid the boats. However, a study was done in 2005 that aimed to study the diving behavior of a solitary male bottlenose dolphin and determine if the presence of boats would cause any behavioral changes.

Figure 2. A group of bottlenose dolphins seen near a boat

            The study was done within a bay on the north-western coast of Spain. Daily observations were made to study the male dolphin’s diving behavior, including accurate measurements of the length of time spent in a dive. The results found that the solitary male bottlenose dolphin did not change his diving behavior as a result of boat presence. This may have been because the movement of the boats in the bay were slow and predictable, or because the dolphin was habituated to the stimulus of the boats. More studies are needed to figure out the exact effects boats have on dolphin behavior and this type of study is important in helping make more informed decisions on factors affecting the wellbeing of bottlenose dolphins.

References:

Díaz López, Bruno, et al. "Diving activity of a solitary wild free ranging bottlenose dolphin (Tursiops truncatus )." Journal of the Marine Biological Association of the United Kingdom, vol. 88, no. 6, 2008, pp. 1153-1157. OhioLINK Electronic Journal Center, doi:10.1017/S0025315408000921.

NOAA. “Bottlenose Dolphin (Tursiops truncatus).” NOAA Fisheries, 16 Jan. 2015, www.nmfs.noaa.gov/pr/species/mammals/dolphins/bottlenose-dolphin.html.

Dolphins tear up nets as fish numbers fall

As we all know, fisheries are an important food sources to us, especially those who live in the coastal areas. There are industrial fisheries that work on large spatial scales of marine ecosystems, as well as small scale industries, which are on more local spatial scales. Such animals that are fished be fisheries include: salmon, cod, tuna, mullets, squid, oysters, scallops, crabs, lobsters, shrimps, and many more marine species. Sometimes because of our fishing activities we have caused much environmental problems to the marine ecosystems including overfishing, and accidental bycatch which has cause population declines in target species as well as non-target species. Such population declines of various species can disrupt the marine food web and cause problems in trophic cascades. This can overall, decrease the biodiversity of such marine ecosystems. In this news article, scientists of the University of Exeter, have been studying how the fisheries of the Mediterranean Sea impact the bottlenose dolphins, as well as how the dolphins impact the fishing business.

Most of the Fishing business of the Mediterranean sea are small scale operations, which has cost them thousands of euros to fix the damage the dolphins caused on their fishing nets. They seemed to have learned to associate the nets with the fish they catch. So, lately they have been stealing the fishes from the nets as an easy food source, instead of actually hunting for the fish themselves, as said by lead author Robin Snape, of the Centre for Ecology and Conservation on the University of Exeter's Penryn Campus. Such problems have probably resulted in low fish stocks, which in turn have lead low catches due to the dolphins. However, even though the dolphins seem to be taking advantage of the nets and tearing them up, there is still the risk of such organisms being entangled and drowning. The authors have estimated that about ten dolphins in the Mediterranean die due to entanglement and drowning from the nets. Much of the funding for this study came from the Society for the Protection of Turtles.


Dolphins tear up nets as fish numbers fall

Extinction in Sharks

I found a research article regarding extinction in sharks, skates, rays, and chimaeras in different oceanic habitats.  Sharks, skates, rays, and chimaeras make up chondrichthyans.  They are compared amongst different habitats, which include: continental shelves, the deep sea, and the open ocean.  Overall, the chondrichthyans that dwell in the deep water have an overall higher rate of maturity and longevity.  Extinction risk was highly associated with phylogeny and reproduction.

Fig 1: Shark

The traits that are often associated with susceptibility to extinction are: low productivity, smaller litter sizes, slower growth rates, slower sexual maturity, and long "interbirth" intervals.  As stated earlier, the different habitats are: the continental shelf, the deep sea, and the open ocean.  The continental shelf is the zone of the ocean that goes from the shoreline to 200 meters deep, the open ocean goes deeper than the continental shelf, and the deep sea goes all the way to the largest depth of the sea.  

In comparison to fishes that live within the shallow-water, deep-water fishes have a slower growth rate, sexually mature later, live longer, and have smaller metabolic rates.  All of these factors cause them to have longer turnover times, which implies that the populations will be less productive.  Predation increases with an increase in metabolism and accelerated turnover rates.  Predation is moderate in both shallow habitats of continental shelves as well as the deep sea.  

The first step of this research paper is to figure out whether deep-water chondrichthyans have a longer turnover time than shallow-water chondrichthyans.  The second step of the paper is to show the consequence of the habitat and life-history traits on extinction.  

In order to complete the experiment, scientists chose 105 different species.  The took data on maximum body size, size at maturity, longevity, age at maturity, growth completion rate, litter size, the interbirith interval, reproduction mode, and habitat.  

Overall, the study concluded many vital aspects of the chondrichthyan habitat.  Firstly, the results from this study showed that the extinction of chondricththyans is indeed linked to habitat.  The chondrichthyans that occupy the deep water have enlarged turnover times.  Chondrichthyans that occupy the shallow and oceanic shelf have a lower extinction risk than those in the deep water.

It was also concluded that reproduction played a role in extinction.  It was found that non-matrophic females who reproduce at higher rates have less of a chance in becoming extinct.  The study also concludes that the body size of the fish has little to do with extinction rate.  If extinction were to occur in these fish, it would happen in fish that are extremely large or small.  The study concluded that the two most susceptible species of fish extinction were: Lamniformes and Squaliformes.  The article says that the solution of the problem is, "Minimizing fish mortality in deep-water habitats already exploited and preventing new deep-water ecosystems to be exploited are necessary to avoid the extinction of these species." (Garcia)

Source: Garcia, Veronica B., Lucifora, Luis O., Myers Ransom A. (2008). The importance of habitat and life history to extinction risk in sharks, skates, rays, and chimaeras. The Royal Society, 275(1630).  Retrieved from: http://rspb.royalsocietypublishing.org/content/275/1630/83#ref-49

What is responsible for the "spark" in the ghost knifefish?

The South American ghost knifefish can generate the highest frequency of electricity observed in any animal. Researchers have found that this could be due to an evolutionarily modified sodium channel.

Parapteronotus hasemani, a species of ghost knifefish used in this study

Electric fish produce electrical signals from their electric organs to sense their environment and communicate with others. The Apteronotids (ghost knifefish) use action potentials of specialized cells that originated from motor neurons in the spinal cord to produce electrical signals. Their electric organs exhibit the highest frequency action potentials of any animal, frequently exceeding 1 kHz. They also require no signal from the brain to produce these electrical discharges. The researchers compared genes in electrical and non-electrical fish that encode voltage-gated sodium channels. Sodium channels regulate the number of sodium ions travelling in and out of cells, allowing electrical signals to be generated that regulate cellular functions. Voltage-gated sodium channels open and shut depending on the voltage across the cell membrane. In an ancestor of a group of fish within the Apteronotids, the researchers discovered that the gene that encodes sodium channels in muscle was duplicated.

Image comparing amino acid sequences from Thompson et al. (2018) Rapid evolution of a voltage-gated sodium channel gene in a lineage of electric fish leads to persistent sodium current. 

The gene was able to make sodium channels in the spinal cord throughout the fish's evolution. The motor neurons that control the firing frequency of the electric organs are also located in the spinal cord. The gene also gained a mutation over the fish's evolution that allows the channel to open more frequently, which could explain the electrical organ's high frequency firing.
These sodium channels are only found in the muscles of most animals, so this is a unique characteristic of the ghost knifefish. Sodium channels are often the target of neurotoxins and play a role in several neurological and muscle disorders in humans. Further research on this mutation could help determine the mutations that lead to these disorders in humans.

Male Loggerhead Sea Turtles and Their Breeding Patterns

Figure 1: Male loggerhead traveling inland to breed

A new study from the Faculty of Biology and the Biodiversity Research Institute of the University of Barcelona (IRBio) showed that most male loggerhead turtles go back to nesting beaches to breed, which is a common behavior among female turtles. This study was published in the journal Marine Ecology Progress Series because it breaks the normal paradigm on breeding behavior in these marine turtles and because it also explains how the species itself could also breed in feeding areas or during their travels towards the nesting beaches. The new paradigm that these researches created was that male turtles (Caretta caretta) return to the nesting beachs to breed.

Caretta caretta is a marine species of sea turtle that predominantly lives in tropical and temperate areas around the world. In the eastern Mediterranean, sea turtles nest along the coasts of Greece, Turkey, Cyprus, Libya, Lebanon, and Israel. It was believed before that only female turtles went back to the nesting areas to lay eggs after mating with the male turtles. In the test called philatropic: behavior studies, there is detection, marking, and a genetic study of these female turtles that travel back to the beach to lay eggs.

Figure 2: Female loggerhead laying eggs on a Mediterranean beach

Lecturer Marta Pascual states "Our study reveals the breeding behavior of the Caretta caretta marine turtle to be more complex. In most populations, females turtles are not the only ones with philatropic behavior: males also mate near nesting beaches." To get these conclusions, the UB-IRBio team increased the number of microsatellite markers to analyze gene flow among turtle populations in the Mediterranean area. Their results showed that there was a higher gene differentiation in the nesting beaches in the Mediterranean. This suggested to them that there is a possibility that turtles breed in feeding areas or during their journey towards nesting beaches. Marta then continues to say "Also, if we compare mitochondrial and nuclear markers, we can compare the spreading behavior of male and female turtles in different areas, which shows complex and particular breeding behavior in each area." Philopatry happens in both male and female turtles. There are times though were there is breeding patterns between males and females in locations other than their birth place.

One problem that can factor into this is that breeding behavior can change depending on the population and sexes within the population. The temperature that the eggs are incubated at determines their sex. If the temperature is high, there will only be female turtles when hatching happens. Since the global temperatures are rising, this is causing more females to be born than males, which is upsetting the balance within populations.

Figure 3: Loggerhead sea turtle hatchlings

The ending to this article talked about protecting the species of turtles in the Mediterranean. They said that the genetically differentiated units should be protected. In some cases, the population size is very large, but in most cases, the populations are much smaller. Lastly, they stated that there needs to be more comprehensive studies of different areas to identify bottlenecks and to study the impact of the increase of variability.

Sources:

Universidad de Barcelona. "Male loggerhead turtles also go back to their nesting beaches to breed." ScienceDaily. ScienceDaily, 14 March 2018. <www.sciencedaily.com/releases/2018/03/180314092710.htm>

M Clusa, C Carreras, L Cardona, A Demetropoulos, D Margaritoulis, AF Rees, AA Hamza, M Khalil, Y Levy, O Turkozan, A Aguilar, M Pascual. Philopatry in loggerhead turtles Caretta caretta: beyond the gender paradigm. Marine Ecology Progress Series, 2018; 588: 201 DOI: 10.3354/meps12448

Images from: Google images

Various Pigment Types of Synechococcus Cyanobacteria from Across the World's Oceans

Studies have been done by the University of Warwick that show that bacteria that are crucial to ocean life can shift their color like chameleons to match different colored light across the world’s seas. This is a very intriguing concept, but also very amazing too. It is found that blue light is prevalent in the open ocean (obviously), while green light is prevalent in coastal and equatorial waters. Red light is prevalent in estuaries. The bacteria Synechococcus cyanobacteria contains specific genes that allow it to adapt their pigments to the light sources that are available! Therefore, this bacteria that lives in the open ocean has adapted to take in primarily blue light, whereas the bacteria in estuaries take in red light and bacteria in coastal and equatorial waters take in green light. S. cyanobacteria uses light to capture carbon dioxide from the air and produce energy for the marine food chain. Their genes are altered in such a way so as to thrive in any part of the world’s oceans.

Figure 1: SEM of Synechococcus cyanobacteria

The light that is absorbed is determined by a multitude of factors. One is the tilt of the Earth and the direction of the light from the sun to the Earth. Refraction plays a role to the bending of light. The geography also seems to play into part of the reason as to the light absorbance changes. Blue light is most prevalent in the open ocean, as it penetrates into the deep waters (it is the deepest penetrating wavelength). The prevalence of light changes depending where on the planet you go. In estuaries, says researcher David Scanlan, the light is often red, whereas in warm equatorial and coastal waters, the light is more green. The bacteria have adapted to utilize the changing light intensities to produce efficiently around the globe.

Figure 2: Various pigment types of Synechococcus cyanobacteria from across the world's oceans, grown in culture at the University of Warwick

Scanlan and colleagues analyzed specific gene sequences from S. cyanobacteria in the different water samples from around the globe. What they found was the same genes in bacteria living thousands of miles apart around the globe. The genes are known as “chromatic adaptor” genes, and they are abundant in ocean dwelling S. cyanobacteria which enables “these color-shifting microorganisms to change their pigment content in order to survive and photosynthesize in ocean waters.” If the same bacteria is in the open oceans, warm equatorial waters, coastal waters, and in estuaries, being able to efficiently produce oxygen from carbon dioxide is a useful adaptation. It would be seemingly wasteful to spend more energy in coastal waters or even estuarine waters to photosynthesize blue light if it isn’t the most prevalent light wavelength. The same goes with trying to photosynthesize red light in the equatorial waters, or green light in the open ocean.

Scanlan says that “finding [these bacterial] cells capable of dynamically changing their pigment content in accordance with the ambient light color … gives us a much deeper understanding of those processes essential to keep the ocean ‘engine’ running.” It is understood that paying attention to these microorganisms will help us better predict how the oceans will react in the future to a changing climate with increasing levels of carbon dioxide. If anything, these “key primary producers are potentially excellent bio-indicators of climate change.”

Source for Article:

https://www.eurekalert.org/pub_releases/2018-02/uow-ob022118.php 

Source for Figure 1: 

https://www.sciencesource.com/archive/Synechococcus-Cyanobacteria--SEM-SS2582898.html#/SearchResult&ITEMID=SS2582898 

First Spontaneous Mutant Coral Symbiont Alga Found

Japanese researchers have recently identified the first spontaneous mutant coral symbiont alga that does not maintain a symbiotic relationship with its host. The alga have devised a system where the simple addition or depletion of a nutrient can switch the symbiosis on and off, experimentally. This alga, which is mutant, enables the development of a genetic transformation system. This system will eventually be a powerful tool for researchers studying coral-algal endosymbiosis.

Figure 1. Symbiotic and non-symbiotic state of the sea anemone E.pallida, respectively. 

A great source of biodiversity in the sea is coral reefs. Stable symbiotic relationships between host cnidarian animals and the symbiont dinoflagellate are what the ecosystem relies on. Environmental changes due to globing warming can collapse this symbiosis. An example of this is “coral bleaching”. Understanding mechanisms for maintaining stable symbiosis is extremely difficult.

Figure 2. Coral Bleaching Reference 

The mutant in these coral is deficient of uracil which is a basic compound of nucleic acid. This has appeared to have lost the ability to maintain symbiosis with a model organism. The model organism used in this case is the sea anemone. This is what indicates the simple addition or depletion of the nutrient which can be used as a switch for controlling the symbiotic relationship. The next step in this research is to introduce genetic mutations that are going to be capable of reversing uracil deficiency in the mutant dinoflagellate. This can hopefully provide clues for identifying algal genes responsible for symbiosis.

Source for Article and Figure 1: Tohoku University. 2018. New Mutant Coral Symbiont Alga Able to Switch Symbiosis Off. ScienceDaily. https://www.sciencedaily.com/releases/2018/02/180222103416.htm

Figure 2 Source: 

http://sites.psu.edu/ichen/wp-content/uploads/sites/38297/2016/04/coralbleaching.jpg

Sea Anemones Evolving Toxins May be the Key to Medical Innovation

For years scientists have used the venom from many creatures to create medicines and treatments for various illnesses. To do this, scientists would extract venom from adult animals and then analyze the make up of the venom and use it in various ways. This process has always been done using adult animals, because the thinking was that an animals venom was the same at a larval stage as it would be at the adult stage. But a recent study with sea anemones has proved that theory wrong. Using a species of sea anemone, Nemotostella, also known as the Starlet Sea Anemone, researchers studied the venom development from larva to adult hood and how the venom chemically changes over the span of their developmental stages. Sea anemones being part of the Phylum Cnidaria have stinging cells on their tentacles that inject the venom into their prey called cnidocytes. To study the venom from these animals, researchers cultured these cells in various life stages and looked into the behavior of Nemotostella at each developmental stage.

Researchers began by studying the venom produced by larva Nemotostella. By analyzing the venom and watching the behavior of the larva, they observed that the venom produced at this stage seemed to be used for defense rather offense. As the small larva are floating through the water they are highly vulnerable to predators. The venom they produce helps them fend off predators so that they can grow to an adult. When a predator eats a larva, the larva release highly potent venom which makes the predator spit them out. This helps ensure that the larva can grow to adulthood and eventually reproduce.

Image of Nematosella 

As Nemotostella reaches adulthood its venom changes from that of a defense mechanism, to something to help them catch their prey. The venom chemically changes to better stun and kill potential prey, rather than surprise and disgust a potential predator. While researchers were surprised to find these changes, the changes did not stop with just development, the environment had an impact on the chemistry of the venom as well. As the water salinity, temperature, and food supply changed so did the potency and make up of the venom. This was a completely new aspect of the evolution of the sea anemone that researchers were excited to discover.  

Expression of Nematosella toxins 

The reason that this discovery is such a big breakthrough is due to the potential medical advancements that would be gained from studying the evolution of the Nematosella venom. Because most, if not all, research done on animal venom is venom taken from adult animals, the concept that there is a whole new variety of compounds from venom to look at has researchers thrilled. The possible new drugs, medicines and treatments that could come from studying these new compounds are unlimited. 

Cluster of Starlet Sea Anemones

Another question being asked in the scientific community after this discovery is how "normal" of behavior is it for animals to change their chemical composition as their environment changes? With climate change becoming a major issue around the world, not just for aquatic ecosystems but for terrestrial ecosystems as well, if scientists can study this further then perhaps they can understand ways to help other organisms change and adapt to an environment that otherwise would be lethal for them. This research could help millions of organisms have a brighter future in a harsher world. 

Resources: 

Image 3 : http://www.sars.no/research/SteinmetzGrp.php
Image 2: https://elifesciences.org/articles/35014

Image 1: 

ScienceDaily. Retrieved March 18, 2018 from 

www.sciencedaily.com/releases/2018/03/180305101633.htm


Yaara Y Columbus-Shenkar, Maria Y Sachkova, Jason Macrander, Arie Fridrich, Vengamanaidu Modepalli, Adam M Reitzel, Kartik Sunagar, Yehu Moran. Dynamics of venom composition across a complex life cycle. eLife, 2018; 7 

Hermit crab uses 'walking coral' as home

Hermit crabs are well known for making their homes out of empty shells. They will go from shell to shell throughout their lifetime trying to find the perfect fit and to gain better protection. However, it has recently been discovered that shells are no longer the only objects hermit crabs are using for protection. A species of hermit crab located in the Amami Islands, which is part of a chain that stretches southwards from Japan towards Taiwan, has been found to be using solitary corals for their shelter. This species of crab is named Diogenes heteropsammicola, after the species of coral that they inhabit.

Hermit crab (Diogenes heteropsammicola)

This relationship has proved to be mutually beneficial for both the hermit crab and the coral. By using coral as its protective armor the hermit crab no longer has to continue to search and search for new and better shells as it continues to grow. The space in the coral in which the hermit crab sits grows with the crab, so it does not need to search and compete among its species for new homes. In addition, the coral is able to sting, which helps to further protect the crab from predators such as starfish, larger crabs, and octopi.

A type of coral the hermit crab will use (Heteropsammia cochlea)

This relationship is also able to be favorable for the coral as this species of coral is a solitary coral instead of a reef-building kind. Solitary corals are often found on shallow sandy seabeds. With this type of habitat, the solitary coral runs the risk of being buried by sediment and overturned by strong currents. To combat this, corals will develop a partnership with other animals to assist them out of the sand and do the ‘walking’ for them. This is usually seen with marine worms, but is now prevalent in this hermit crabs species as well.

Coral skeleton after being used by hermit crab

Though more research needs to be done, it is thought this relationship with hermit crabs developed similarly to how the marine worms use the coral for protection. In the case of the marine worm, a young coral will settle on a small shell that has already been colonized by the marine worm. The coral then grows over and beyond the shell, providing a cavity for the marine worm, which is continuing to grow as well. These hermit crabs likely acquire coral shelter and develop this symbiotic relationship in a similar manner such as this one.




Mynott, S. (2017). Newly discovered hermit crab species lives in 'walking corals.' The Conversation, 12 March 2018.

Undersea Constellations: The Global Biology of an Endangered Marine Megavertebrate (Whale Shark) Further Informed through Citizen Science

It is challenging to gather ecological data including behaviors and movements on worldwide animals. Such data is gathered from multiple sources because it would be impossible for one group of scientists to collect such data on such a large spatial scale. One approach that has been helpful is citizen science, the collection of data from the general public, which has helped increase our knowledge on animals that inhabit global spatial scales. With such data we can access the abundance, size, sex frequency, and spatial trends of Nursey sites, mating sites, and feeding hotspots of such animals that can help us to better manage and protect a species. An example of an animal that is of critical importance to obtain such data would include the Whale Shark (Rhincodon typus).

Little is known about the Whale Shark, and the knowledge we have on the animal has been recently documented in the past decade. They filter-feeders that aggregate in groups at specific locations throughout the oceans where there is much Planktonic growth, and are distributed between 30°N and 30°S. Their life history includes slow growth, later maturation, and extended longevity, which makes them vulnerable to population declines especially to human threats including bycatch, pollution, ship strike, and targeted fishing which is why it is critical to obtain such spatial data. Ecotourism activities have focused on monitoring such sharks via photo-identification, observing unique skin patterns, thus creating a database of photo-identified sharks. This study reports the success of monitoring the Whale Sharks on the global scale which includes sightings on local and global levels, size and sex ratios over time, locations of common resighting history, and the resighting of individual sharks in one or more countries. 

Figure 1. Unique pattern behind the gills helps identify individual

Photo-identification images are collected when a tourist or a researcher is swimming and takes a picture of a skin pattern that is unique to each individual shark that are long lasting. An example is seen in Figure 1. Such pictures are then uploaded to a database online as well as other information including sight location, sex, and estimated length. Computer-assisted pattern-matching technology is used to determine if the shark is a new shark or if it is a resighted shark. Each encounter is assigned a location code, depending on the country or hotspot where the encounter, or sighting, occurred. Identified sharks are catalogued with a prefix according to the location code from the first identifiable sighting and each newly identified shark is assigned a unique number specific to that sighting location.

Figure 2. Hotspot Distributions of Whale Sharks

From 1992 to 2014 there has been 28,776 whale shark encounters, and 6091 individual sharks have been identified from 54 countries. The authors of this study determined 20 hotspots, or locations that had at least 100 whale shark encounters, which have contributed to 99% of all the documented encounters. As seen in Figure 2, such hotspots include Belize, The Maldives,  South Africa, Tanzania, Mexico–Atlantic region, Honduras, Mozambique, Qatar, Western Australia (Ningaloo Marine Park), The Philippines (Donsol, Leyte, Cebu), Seychelles, Djibouti, Oman, The United States–Gulf States region, Christmas Island, Mexico–Pacific region, Indonesia, Thailand, Red Sea, and The Galapagos. Much of these sites have been identified with the help of the general public including ecotourism activities. Such sightings have been correlated with areas of high primary productivity of plankton. 

Figure 3. Sex ratio of identified whale sharks at global hotspots

As seen in Figure 3 there seemed to be a strong male bias throughout 14 of the previously mentioned hotspots, with at least 66% of the individuals being males. However, at the Galapagos, 99% of the individuals were female, at the Red Sea, 75% of the individuals were female, and in Thailand, 68.5% of the individuals were female. There is also a bias of the juvenile inhabiting the coastal areas. 

Table 1. Average total length

According to Table 1 the longest individuals occur at the Galapagos with an average length about 11.07 meters, followed by the U.S-Gulf States region with an average length of 8.01 meters, Belize with an average of 7.21 meters, Mexico-Atlantic region with an average of 7.12 meters, and all other locations with an average of 7.0 meters. 

Based on the data, the whale sharks tend to be found in localities throughout the year and some may even stay in the same area for an entire year. However, most Whale shark aggregations are very seasonal in which ecotourism activities try to take advantage of. The overall average of sharks returning to the same hotspot within 2 or more years is about 35.7%.

Based on photo-identification, marker tags, and satellite tracking Whale Sharks tend to migrate between local countries, maybe like 1000 km. There are only very few exceptions where the whale sharks migrated across entire oceanic basins. Not much is known about their reproduction, however, many pregnant females are found in offshore habitats, suggesting such areas provide pupping and nursery grounds.

Citation
Bradley M. Norman, Jason A. Holmberg, Zaven Arzoumanian, Samantha D. Reynolds, Rory P. Wilson, Dani Rob, Simon J. Pierce, Adrian C. Gleiss, Rafael de la Parra, Beatriz Galvan, Deni Ramirez-Macias, David Robinson, Steve Fox, Rachel Graham, David Rowat, Matthew Potenski, Marie Levine, Jennifer A. Mckinney, Eric Hoffmayer, Alistair D. M. Dove, Robert Hueter, Alessandro Ponzo, Gonzalo Araujo, Elson Aca, David David, Richard Rees, Alan Duncan, Christoph A. Rohner, Clare E. M. Prebble, Alex Hearn, David Acuna, Michael L. Berumen, Abraham Vázquez, Jonathan Green, Steffen S. Bach, Jennifer V. Schmidt, Stephen J. Beatty, David L. Morgan; Undersea Constellations: The Global Biology of an Endangered Marine Megavertebrate Further Informed through Citizen Science, BioScience, Volume 67, Issue 12, 1 December 2017, Pages 1029–1043, https://doi.org/10.1093/biosci/bix127
Hyperlink:
https://academic.oup.com/bioscience/article/67/12/1029/4641655
file:///C:/Users/Tyler/Desktop/Marine%20Biology/Whale%20Shark.pdf