Critter of the deep - Episode 1: Secrets of the Ram's horn squid

Have you ever seen these shells on the beach?

Secrets of the Ram's horn squid

Sadie Mills is the Collection Manager of the NIWA Invertebrate Collection (NIC), a Nationally Significant Collection and Database holding over 300,000 jars of preserved marine invertebrates from around New Zealand, Antarctica and the wider South West Pacific. Sadie is responsible for the NIC staff and volunteers and manages the MBIE SSIF funded project that supports the long-term care and enhancement of the Collection.

The Ram’s Horn squid (Spirula spirula) is a mesopelagic species, meaning that it lives in the mid-water column. It typically lives in dark depths of 500-1000 m in the day and migrates up to the shallows of 300 m at night, part of its diurnal vertical migration pattern (one of the largest daily mass migrations in the world.)

Spirula specimens have been collected from tropical and subtropical waters worldwide. As the shells are very buoyant they wash up on beaches all over the world!

This species was described by Carl Linnaeus, the father of modern taxonomy, way back in 1758. He originally named it Nautilus spirula, but it has since been transferred to the genus Spirula. Spirula shares similarities with the Nautilus, Cuttlefish and the extinct ammonites and belemnites as they all have a multi-chambered shell, rather than a pen like other types of squid.