Category: Invertebrates

Compound Setae of a Sea Spider: An Adaptation for Grooming

Cormac Toler-Scott

Award winner

Sea spiders are an enigmatic group of marine arthropods considered the sister group to arachnids. They exhibit exclusive paternal care, the rarest form of parental care among animals. With a special pair of appendages modified for egg carrying called ovigers, male sea spiders collect eggs from a female and fertilize them before cementing them to their ovigers until they hatch. Some sea spiders like the one pictured above have compound setae on their ovigers which give the ovigers another function—grooming. These comb-like setae can be scraped along the sea spider’s body to remove debris and parasites.