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| Blue Damselfish |
We’ve all heard the term ‘damsel in distress’ when
describing some poor, helpless person who is screaming in the grips of a
villain and is in need of the help of a heroic stranger to save their
life. That role has been played out in
Hollywood countless times. But what if
it this scenario actually happened? As
it turns out, Damselfish (appropriately named) seem to do this type of thing
when they are caught by predators. These
coral reef dwelling fish send out a chemical signal when injured that actually
increases their chance for survival.
Scientists have known that Damselfish release chemicals from
their skin when they are injured which causes other nearby fish to flee, but
they recently have found that these chemicals also attract more predators to
the scene of the crime. Attracting more
predators doesn’t sound like a good strategy for the Damselfish at first (MORE predators, are they nuts?!) but having
more predators around causes interference with the initial predation event,
giving the Damselfish a greater chance for escape. The other predators are likely to try to
steal the Damselfish from the initial attacker.
The commotion of competition gives the prey a greater chance to wiggle
free and escape with its life. A study
found that when there is another predator at the capture site, the prey is up
to 40% more likely to escape.
This is the first evidence scientists have found of the
chemical signals released by captured prey actually increasing the prey’s
chances for survival instead of just the other fish’s chances for survival by
causing them to run away from the area.
Scientists have known for a long time that many organisms send out alarm
cues but they didn’t know what advantage it served the sender until recent
experiments. It is thought that alarm
cue cells originally evolved to protect fish from bacterial infection when
there was tissue damage and they later developed secondary predator attracting
qualities to help them escape from attackers.
They also think that the secondary predators have evolved to become
sensitive to the chemical distress signals so they can gather important
information from them, helping them decide whether or not it is worth trying to
steal the potential meal.
If you’re a fish, being a damsel in distress can have its
advantages. In the case of the
Damselfish, it may even be lifesaving.
References
When setting up aquariums in your homes the stores say you should use a damsel fish as your starter fish in your tank. After reading this I don't think I would want to use them because of the chemicals they realize that could cause the other fish in the tank to die.
ReplyDeleteI believe that damsels are suggested since they are very hardy and most likely to survive until the biological filter system in the tank has matured by growing a strong population of bacteria. According to Krista's post, it sounds like these chemical attractants would only be released during a predation event, and they don't harm other fishes.
ReplyDeleteThat's very interesting! Another interesting characteristic of damselfish I found in a paper published last year is that they can identify predation risk through their sense of smell while they are larvae. As we have discussed in class, organisms are at such great risk of predation while larvae that larvae biomass is not reflective of mature population biomass. With this in mind, the ability to sense predators early on through smell could greatly benefit larval survival rates and possibly affect their settlement location and behavior, as the paper mentions.
ReplyDeleteSource:
Animal Behaviour
http://www.sciencedirect.com/science/article/pii/S0003347215000433