The elusive ram’s horn squid

By Alex Scott

The ram’s horn squid, or Spirula spirula, is one of the most elusive cephalopods in the world. This tiny squid is only three inches long, lives in deep regions of the ocean, and until very recently had never been discovered in its natural habitat. What little marine biologists do know about the ram’s horn squid comes from studying the very few captured specimens in aquariums.

But for beachcombers, ram’s horn squid is most interesting for its delicate, coiled shell, which the squid itself is named after. The squid is also known as the little post horn squid, or—as it has a light-emitting organ on one end—the tail-light squid. The ram’s horn squid uses its tightly coiled shell as a buoyancy organ to travel up and down through the tropical and temperature regions of the deep ocean. While other molluscs such as the nautilus have external chambered shells, the cuttlefish and ram's horn squid are the only that use internal shells to regulate buoyancy. Due to its extreme buoyancy, ram’s horn squid shells wash up on beaches across the world for shell collectors to find. As a result, we know much more about the animal’s shell than anything else about this tiny squid.

Vintage illustration from Meyers Konversations-Lexikon 1897, Hein Nouwens.

In October 2020, a group of scientists at the Schmidt Ocean Institute were operating a remotely operated vehicle (ROV) through the Great Barrier Reef (off the coast of Queensland, Australia), when they suddenly came across a ram’s horn squid, swimming at over 2,700 feet in depth. This encounter was later confirmed to be the first sighting of a ram’s horn squid in its natural habitat, and marine biologists across the world were thrilled. They were very interested to discover that the ram’s horn squid swims with its head pointed up towards the surface, which aquarium specimens do not do. The wild squid also may have squirted some ink at the ROV, which is another rare behavior for deep sea animals.

Framegrabs from the 4K video record of Spirula spirula observed in situ from The First In Situ Observation of the Ram’s Horn Squid Spirula spirula Turns “Common Knowledge” Upside Down by Dhugal J. Lindsay, James C. Hunt, Mardi McNeil, Robin J. Beaman, and Michael Vecchione, MDPI.

Unfortunately for those scientists interested in ram’s horn squids, although they are not an endangered species, they are extremely rare. Luckily for beachcombers, their beautiful coiled shells are much easier to find and make into beautiful jewelry. Just think of the incredible journey those shells have taken, from the very bottom of the ocean up to the sandy beach.

See how a jeweler creates earrings casted from a ram's horn squid shell.

This article appeared in the Beachcombing Magazine March/April 2021 issue.

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