Amazing Shells of the Academy of Natural Sciences of Drexel University

The Malacology Collection at the Academy of Natural Sciences of Drexel University in Philadelphia dates back to the institution’s founding in 1812, when one of its founders donated a box of shells and madrepores (reef-building corals). Since then, the shell collection has grown considerably and now occupies more than 250 cabinets containing more than 13,000 drawers and 10 million specimens, together weighing more than 55 tons. The collection represents every region of the world and is a priceless resource for scientists in many disciplines. It is fully searchable online through the Academy’s website, ansp.org, and more than 5,000 of the most scientifically important specimens can be viewed as high-definition images on any web browser.

This large species lives on sand in shallow water in the Red Sea and throughout the Indian and western Pacific Oceans. It grows in regular increments, with each new section a larger version of the previous one; the large horns do not fully develop until the final stage. Adults can live for many years, their shells gradually eroding and acting as a home to sponges, corals, boring bivalves and other marine organisms.

This dramatic shell was named by R. Tucker Abbott, the third chairman of the Malacology Department at the Academy of Natural Sciences, for his predecessor Henry A. Pilsbry. It is known exclusively from the Marquesas Islands in the Indian Ocean, where it lives on sand in shallow water.

This shallow-water marine species demonstrates the sense of building a shell that is as large and hard to bite as possible. The animal creates the spines by forming its flesh into long, narrow tubes and filling them in with shell material. It was first scientifically named in the auction catalog of the collection of the Duchess of Portland in 1786, though it was known in China and Japan as “fish-bone shell” long before that.

This shell is also called the Paper Nautilus, but the animal that makes it is actually an octopus that lives in the open ocean. The shell is only made by females, and its function is to protect the animal’s eggs until they hatch. The light but surprisingly rigid shells are sometimes cast up on beaches after storms and can be found in almost all parts of the world. There are several species, of which Argonauta argo is the largest.

This marine species is highly variable in color and the length and shape of its spines. It lives permanently attached to hard objects like rocks or piers, and in life it is covered with algae and sponges that settle and grow among the spines, concealing the animal altogether. The bright colors and patterns are only revealed with careful cleaning. It can be found from North Carolina and Texas to Brazil, in shallow to moderately deep water. Spectacular specimens are often collected by divers from the legs of oil drilling platforms.

This is a slit shell, one of fewer than 30 surviving species in an ancient family that was very abundant in all oceans from the Cambrian to the end of the Cretaceous era. The slit is a natural feature; it forms a duct that channels water out of the animal’s gill cavity. Slit shells have long been known as fossils but were thought extinct before a living one was found for the first time off the West Indies in 1879. They have since been found in South Africa, Australia, Japan and elsewhere.

Found in the Indian and tropical west Pacific Oceans, these large marine snails are a traditional source of food in island communities. Tools and ornaments made from their thick shells are known from prehistoric sites in many parts of the Pacific, and their fine mother-of-pearl is still favored for inlay work, especially in Korea and Japan. The operculum, a trap door that seals the shell when the animal retreats inside, is thick and heavy.

The False Melon is named for its resemblance to its larger relative, the Melon Shell. A nocturnal marine carnivore, it feeds on mud-dwelling invertebrates. The large, bulb-like end is actually the preserved infant shell, which is set at an angle to the adult shell. This species is known only from southeastern Australia.

This formerly rare marine species belongs to a huge family of carnivorous snails that use powerful venoms to paralyze their prey. Depending on the species, their target can be fish, worms or other mollusks. Strong demand for their gorgeously patterned shells among nineteenth-century collectors led to the creation of convincing fakes from wood, clay or other shells. Most specimens nowadays are from the Philippines, where the species lives in moderately deep water and is active at night.

These tropical marine bivalves live attached to solid surfaces on the sea bed. Their shells resemble those of other oyster families in having a layered, pastry-like construction and a partial mother-of-pearl lining inside. There are several species of Hammer Oyster, all sharing the characteristic “T” shape.

The Amphidromus snails of the Philippines and Indonesia are unusual in that - as their name implies - their shells can coil either clockwise or anti-clockwise, sometimes even within the same species. They also vary greatly in color and pattern between localities, often making it difficult to define the species. This color form was named versicolor by Fulton in 1896, but is thought to be a local variant of quadrasi. In common with the myriad other animals of the tropical jungles in their region, the habitats of the Amphidromus snails are seriously threatened by agriculture and mining.

The tusk shells are a separate group from the snails, clams and other mollusks, and are known from all world oceans. They are thought to be the last molluscan class to evolve, though much remains to be learned about their derivation. Fully marine, they live partly buried in mud and sand on the sea bed. Historically, their distinctive shells were used as money and decoration by societies in different parts of the world. The bright green Elephant Tusk is found from the Red Sea to the Philippines and is relatively common.