The deep-sea spiny eels are a family, Notacanthidae, of fishes found worldwide below 125 metres (410.1 ft), and going as deep as 3500 metres (11,482.9 ft).

Their bodies of deep sea spiny eels are greatly elongated, though more tapered than in true eel

Eel

Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...

s. The caudal fin is small or nonexistent, while the anal fin is lengthy, as long as half of the total body length. They feed on animals attached to or living on the sea floor, such as sea anemones, echinoderm

Echinoderm

Echinoderms are a phylum of marine animals. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone....

s, molluscs, and worms.

Although they are not true eels, these fish do have a similar leptocephalus

Leptocephalus

A leptocephalus is the flat and transparent larva of the eel, marine eels, and other members of the Superorder Elopomorpha. Fishes with a leptocephalus larva stage include the most familiar eels such as the conger, moray eel, and garden eel, and the freshwater eels of the family Anguillidae, plus...

 larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

. However, while the larvae of true eels are about 5-10% of the length of the adult, those of deep sea spiny eels can grow considerably larger than the adult, and shrink when they develop into their final form. Thus, while adults range from 20 centimetres (7.9 in) to 1.2 metres (3.9 ft) in length, larvae of up to 1.8 metres (5.9 ft) have been recorded.