Lobsters are generally notable for their large claws, which can serve as a deterrent to any predators. But there’s a whole family of spiny lobsters that lack these claws. They tend to ward off predators by forming large groups that collectively can present a lot of pointy bits towards anything attempting to eat them. In fact, studies found that the lobsters can sense the presence of other species-members using molecules emitted into the water, and use that to find peers to congregate with.
A new study, however, finds that this same signal may lure young lobsters to their doom, causing them to try to congregate with older lobsters that are too big to be eaten by nearby predators. The smaller lobsters thus fall victim to a phenomenon called an “ecological trap,” which has rarely been seen to occur without human intervention.
Lobsters vs. groupers
The study was performed in the waters off Florida, where the seafloor is dotted by what are called “solution holes.” These features are the product of lower sea levels such as those that occur during periods of expanded glaciers and ice caps. During these times, much of the area off Florida was above sea level, and water dissolved the limestone rocks unevenly. This created an irregular array of small shallow pits and crevices, many of which have been reshaped by sea life since the area was submerged again.
The crevices offer a great gathering place for spiny lobsters, which can congregate in a way that ensures their spiky bits are all arranged to effectively block an attack from the limited directions of approach. Unfortunately, they are also home to groupers, large fish that are capable of gulping down the smaller lobsters. But groupers don’t have the jaws to break down the shells of larger ones, rendering more mature spiny lobsters immune from their predation.