Most marine invertebrates, including a majority of the world’s sea urchins, wouldn’t win an award for good parenting. Their child-rearing role typically ends when they release their eggs and sperm into the sea. However, Antarctic urchins are different. This species harbors their developing young in special pouches or indentations, located between their multiple spines. This behavior, called brooding, is evident in at least three separate lineages of Antarctic sea urchins.

During a month-long research trip to Antarctica, Academy scientist Dr. Rich Mooi and his student, Suzanne Lockhart, collected a large number of brooding sea urchins, some of which represent new species. One newly discovered species actually stores its developing young in depressions around its mouth, or even among the spines and in deep depressions on the top of its body. Another species broods its young in pouches located inside its body, and when the young are fully developed, appears to give birth, as the plates around an opening on its body fold down.

With their brilliant hues and ornate tentacles, nudibranchs—or sea slugs as they’re commonly called—are visually striking animals. They occupy a wide range of aquatic habitats, ranging from polar waters to tropical seas, from shallow reefs to deep-sea trenches. A few species are even found in tropical freshwater rivers. To date, more than 3,000 species of sea slugs have been discovered, and scientists estimate there are at least another 3,000 species yet to be documented.

Dr. Terry Gosliner, senior curator of invertebrate zoology at the Academy, has been working for the past ten years on a comprehensive field guide to Indo-Pacific nudibranchs. When completed, Gosliner’s catalog will feature photos and detailed descriptions of more than 1,500 different sea slug species. This reference guide will be a valuable resource for recreational divers, conservation biologists, and nudibranch specialists.

For hundreds of millions of years, Earth’s organisms have been engaged in a longstanding battle. Known as the biological arms race, or the Theory of Escalation, predator and prey continually evolve better methods and tools to “outdo” one another and to gain an edge in the struggle for survival.

Academy scientist Dr. Peter Roopnarine and his colleague, Amy Beussink, recently found evidence of this ancient war. While sifting through the fossil record, Roopnarine noticed a small opening drilled into the protective shell of a Chione erosa clam. A predatory species of snail fed on this species, eventually leading to its extinction. When the fossil record turned up the next closest relative of this clam species—Chione elevata—scientists found that these clams had evolved thicker shells, forcing the snails to adapt their predatory habits.

By studying other fossils as well as present-day invertebrates, Roopnarine continues to gain insight into the never-ending war between predator and prey.