Sea bunnies, scientifically known as Jorunna parva, are a species of dorid nudibranch, a type of shell-less marine gastropod mollusc. Their popular name comes from their distinctive appearance, featuring two ear-like rhinophores and a body covered in small, rod-like structures called caryophyllidia that give them a furry texture. Despite their resemblance to fluffy terrestrial rabbits, these marine invertebrates reproduce by laying eggs.
Sea Bunny Reproduction
Sea bunnies are simultaneous hermaphrodites, meaning each individual possesses both male and female reproductive organs. When two sea bunnies encounter each other for mating, they engage in a reciprocal exchange of sperm. Each acts as both a sperm donor and a recipient.
After the sperm exchange, both individuals can then fertilize their own eggs internally. This reproductive strategy increases the chances of successful reproduction within their relatively short lifespan, which typically ranges from a few months to a year. The ability for both partners to lay eggs after a single mating encounter is a common adaptation among many nudibranch species.
The Appearance of Sea Bunny Eggs
Following successful fertilization, sea bunnies deposit their eggs in intricate, often spiral or ribbon-like structures. These egg masses are typically gelatinous and meticulously attached to hard surfaces within their marine habitats, such as rocks, algae, or sponges.
The color of these egg ribbons can vary, but they are frequently white or yellowish, often mirroring the coloration of the adult sea bunny itself. Each ribbon contains a large number of tiny individual eggs, sometimes numbering in the hundreds of thousands or even up to a million, depending on the nudibranch species and the size of the laying individual.
The Sea Bunny Life Cycle
The sea bunny life cycle begins with embryonic development inside laid egg masses. After a period of development, the eggs hatch into a free-swimming larval stage known as a veliger larva. These microscopic veliger larvae are planktonic, drifting in ocean currents.
Veliger larvae are characterized by a tiny, temporary shell and a ciliated structure called a velum, which they use for both swimming and feeding on phytoplankton. This larval stage aids in dispersal. The veliger eventually undergoes metamorphosis, where it settles onto the seafloor, sheds its larval shell, and transforms into a benthic (bottom-dwelling) juvenile. The juvenile then grows into the adult sea bunny, continuing the cycle by feeding on specific sponges and other small marine organisms.