A slender deep-water squid trailing two tentacles several times the length of its own body.
A small slender body with a long tail-like extension and two enormously elongated tentacles trailing behind, ending in expanded clubs. The whole animal is soft, largely transparent, and often carries scattered dark chromatophores. It is unmistakable when the tentacles are extended and easy to misidentify when they are drawn in, when it can pass for any other small pelagic squid.
Chiroteuthids live in deep water as adults and hang almost motionless, with the tentacles hanging below as a passive trap for small crustaceans and fish. Buoyancy comes from ammonium ions held in the tissues, so the animal can hover without swimming. The young stage is elongated in a different way again, with a long tail carrying the fins well behind the body, and it was originally described as a separate genus before the connection to the adult was made.
What is met on a blackwater dive is a juvenile that has risen with the nightly migration. Several species occur in the Indo-Pacific and they are separated on details of the tentacle clubs and the photophores, which a single photograph rarely shows well; the genus is usually as far as an in-water record can honestly go. The tentacles are fragile and the animal will withdraw them under a strong light, so the picture that shows what the animal is has to be taken early.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.
