In 1977 near the
Galapagos islands scientists first observed that hydro-thermal vents helped
create a thriving deep-sea habitat. For the first-time creatures such as crabs,
snails, and bivalves were seen using this rich source of nutrients in an
otherwise barren place to thrive. Almost 40 years later in 2015, scientists
took the ROV (remotely operated vehicle) Hercules down to the
observe these vent systems and the variety of life that lived within them they
noticed something unusual. What appeared to be egg capsules both old, and currently
in use were crowding the vents.
They observed that these capsules were located very close to the
vents and that there was an abundance of old egg capsules which showed that
this
process had been going on
for quite some time. After collecting samples of the egg cases for DNA resting
and taking careful measurements of the cases the species was determined to
be Bathyraja spinosissim, which is a species of Deep Sea
Skate, a relative of the shark. These creatures have one of the longest incubation
periods of almost any creature in the animal kingdom, which seemed to make
sense as to why they would choose to lay their eggs here to incubate.
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The
heat given off from the hydrothermal vents seemed to help speed up the
incubation period for the skates. Other animals in this genera, such as
B. parmifera which resides in the Bearing Sea, and has an
incubation period of almost 1290 days at 4.4 degrees Celsius. So, if the
Pacific White Skate has a time frame for development much like its
relative, then with the water being at an average temperature of 2.76 degrees
Celsius, the estimated incubation period would be around 1500 days.
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Studies have shows that there is a positive correlation for water
temperature and incubation period, so with that being a main factor
contributing to the hatch rates of the skates then it would make sense that
they would lay their eggs near the vents where the water would be warmer and
incubation time would be cut down.
Not
only was the water temperature an ideal place for the skates to lay their eggs,
the environment also has an ample food supply and ideal shelter. The vents have
a wide variety of creatures living there as well, so when the young hatch they
can be sure they will not starve. The vents plumes of black smoke also help
provide coverage for the young skates against any potential predators giving
them a small advantage at the start of their lives, so temperature may not be
the only influential factor to skates when they choose where to lay their eggs.
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| Figure 2. Skates egg capsules |
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This
study has helped marine biologists to get a better understanding as to the
behavior of the skates and given them ideas on how to help conservation efforts
to raise the sates population. With this study being the first time that
skates’ eggs have been found in extremely high density it has given
conservationists ideas to what they should look into when creating reserves for
skates to breed, lay eggs, and thrive in creating a more positive outlook for
this species survival.
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Click here for a short video showing the ROV's trip to the egg incubation site
References:
https://news.nationalgeographic.com/2018/02/Pacific-white-skate-eggs-hydrothermal-vents-animals/
https://www.nature.com/articles/s41598-018-20046-4
http://www.newsonia.com/reader/report/deep-sea-skates-use-hydrothermal-vents-as-egg-incubators/
Images and video from :https://www.nature.com/articles/s41598-018-20046-4
http://www.newsonia.com/reader/report/deep-sea-skates-use-hydrothermal-vents-as-egg-incubators/
A four and a half year incubation period is an enormous amount of time to develop the organism and to maintain its population size. If the incubation period is so long, it makes one wonder for what purpose, besides that they are designed for such a thing. I did a little research and found that elephants have the longest gestation period as mammals go. But black alpine salamanders, tiny little things, carry their young for 2-3 years! That is quite the size difference, though the altitude seems to have an effect on the salamanders. The next on the list would be some sharks, like the Frilled Shark, where they can carry their young for 3.5 years before giving birth. That is just crazy. But seeing as though this species may be in competition with the deep sea octopus (an incubation period of 4.5 years), the deep waters have a deep mystery. There is still so much we don't know regarding the deep ocean, and finding over a four year incubation period is one of them!
ReplyDeleteI think this is such a cool discovery. It's not something you hear about every day, and for good reason. I did some searching on similar articles and found that this is the first time that an animal has been witnessed to utilize hydrothermal vents for incubation. The use of external heat sources is not a common reproductive strategy. Although some factors of reproduction, like sex, are determined by soil temperature in some reptiles, the specific choosing of a hot habitat is not common. In fact, skates are the only marine organism known to do this. The only other animals known to use volcanic heat to incubate their eggs are the neosauropod dinosaurs and the rare Polynesian megapode. For a closer look at some of these details, here is the link for the article I checked out: https://www.sciencedaily.com/releases/2018/02/180212121226.htm
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