Bryozoans sieve food particles from the water with their tentacles.Credit: Marek Mis/SPL
The Ocean’s Menagerie
Drew Harvell Viking (2025)
Life on Earth began in the sea. There, invertebrates emerged roughly 700 million years ago — some 200 million years before their spined cousins, the vertebrates.
“The more I learned,” writes marine ecologist Drew Harvell, “about the critters in the oceans without backbones—the corals, sponges, worms, jellyfish, clams, crabs, and octopuses that make up 99 percent of diversity in the oceans—the more awe I felt in seeing the marvellous adaptations they had for getting food, reproducing, and avoiding their killers in an environment spinning with an abundance of life.” She calls her appealing book exploring this underwater universe, written after a lifetime of study, “a deep dive”.
The turning point of her career came while working on the remote Pacific shores of the Salish Sea, on the border between Canada and the United States. She witnessed that, when exposed to a predator, Bryozoa — creatures that resemble corals and are often referred to as ‘moss animals’ — grow “a forest of long, dense spines”. In other words, they shift into a form that is “as different as another species” is.
Her tour of wondrous animals, from extremely strong corals to sponges that release compounds now used as drugs, shows how climate change threatens their existence. We need to conserve this “menagerie” — not least to ensure the survival of our own species.
Sex Is a Spectrum
Agustín Fuentes Princeton Univ. Press (2025)
A tropical Atlantic fish, the bluehead wrasse (Thalassoma bifasciatum), launches this fascinating book about sex. Females produce eggs and males make sperm. But if the group’s largest male gets killed, a female takes over by rapidly altering its reproductive organs to become the main sperm producer.
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