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An hourly guide that follows twenty-four mollusks to reveal the fascinating lives behind their shells.

From morning to night and from the Arctic to the equator, snails, clams, and other shell-making mollusks have busy days. In this short book, acclaimed author and marine biologist Helen Scales shows readers exactly how these animals spend their time. Each chapter of Shell Day features a single mollusk during a single hour, highlighting twenty-four different species.

Far in the north, the Svalbard archipelago lies deep in the darkness of the polar night. And yet, in what remains a scientific mystery, Iceland scallops continue their daily rhythms, closing and opening their fan-shaped shells using an internal clock. At noon, we observe a clam shell sitting still on the seabed of a sandy tropical lagoon. The two shells open slightly, and a pair of rounded eyes peep out. A small, rust-colored coconut octopus hiding inside lets the clam shells fall apart and gathers them up in her arms. This mollusk’s ancestors long ago lost the ability to produce their own shells, but the cephalopod is happy to use another animal’s castoff as a temporary home. At ten that night, we find ourselves in Southern France. A male moon snail uses his huge, fleshy foot like a plow as he digs down into the seabed in search of food. When the moon snail finds a cockle, he swiftly smothers it, then sets about drilling, aided by a daub of acidic slime. Cockles are tasty, but so are other moon snails, and his snacking has a cannibalistic flavor.

For each chapter, illustrator and cartoonist Aaron John Gregory has depicted molluscan scenes with entrancing pen-and-ink drawings. Working together to narrate and illustrate these unique moments in time, Scales and Gregory have created an engaging read that is a perfect way to spend an hour or two—and a true gift for beachcombers, naturalists, or anyone eager to learn about the mollusks that make their favorite shells.

A global analysis of the effects of social security reforms on the retirement incentives and labor force trends of older workers.

Employment among older men and women has increased dramatically in recent years, reversing a downward trend in the closing decades of the twentieth century. Social Security Programs and Retirement around the World examines how changing retirement incentives have reshaped labor force participation trends among older workers. The chapters feature country-specific analyses for Belgium, Canada, Denmark, France, Germany, Italy, Japan, Netherlands, Spain, Sweden, the United Kingdom, and the United States. They find that while there is significant heterogeneity across countries, the reforms of recent decades have generally reduced the implicit tax on work at older ages. These changes correlate positively with labor force participation. The studies exploit the variation in the timing and extent of reforms of retirement incentives and employ microeconometric methods to investigate whether this correlation reflects a causal relationship. Policy changes appear to have contributed to rising labor force activity, but other factors like the role of women in the labor force, improved health, and changes in private pensions likely also play important roles.

In this lavishly illustrated, first-ever book on how spider webs are built, function, and evolved, William Eberhard provides a comprehensive overview of spider functional morphology and behavior related to web building, and of the surprising physical agility and mental abilities of orb weavers. For instance, one spider spins more than three precisely spaced, morphologically complex spiral attachments per second for up to fifteen minutes at a time. Spiders even adjust the mechanical properties of their famously strong silken lines to different parts of their webs and different environments, and make dramatic modifications in orb designs to adapt to available spaces. This extensive adaptive flexibility, involving decisions influenced by up to sixteen different cues, is unexpected in such small, supposedly simple animals.

As Eberhard reveals, the extraordinary diversity of webs includes ingenious solutions to gain access to prey in esoteric habitats, from blazing hot and shifting sand dunes (to capture ants) to the surfaces of tropical lakes (to capture water striders). Some webs are nets that are cast onto prey, while others form baskets into which the spider flicks prey. Some aerial webs are tramways used by spiders searching for chemical cues from their prey below, while others feature landing sites for flying insects and spiders where the spider then stalks its prey. In some webs, long trip lines are delicately sustained just above the ground by tiny rigid silk poles.

Stemming from the author’s more than five decades observing spider webs, this book will be the definitive reference for years to come.