Many ocean creatures send their planktonic babies, or larvae, into offshore waters to grow and develop while they also look for a home. Yet the sea is vast and the dangers are many! There is only a very slim chance that a larva will find its way to a place it can call home and safely transform into an adult. For larvae whose adults live on wave-exposed rocky shores, the survivors will be those that seize the rare opportunity to transition to adult life when the conditions are right. How do they figure this out?
Recent research by Dr. Matt Ferner and his colleagues shows that when immature larvae of sea urchins drift in from sea towards appropriate coastal habitat, they can use a habitat cue to speed up their development and complete metamorphosis into an adult before they get swept back out to sea. The cue for baby urchins and other animals they have studied that live in similar habitats, is the turbulence from breaking waves. Marine animals living in places without crashing waves may respond to high levels of turbulence in different ways.
They learned about this habitat-related turbulence cue through careful laboratory studies mimicking key aspects of the turbulence experienced in nature. Interestingly, these developmental responses change as the larvae get older and in some species their responsiveness appears to be an inherited trait. This suggests natural selection might act on this trait and could be involved in the evolution of species.
Matt Ferner and his colleagues plan to continue studying how these kinds of cues might contribute to the formation of different species. Next steps involve comparing closely related species that have evolved to specialize in different kinds of habitats, from the deep sea to the wave-battered outer coast.