Fish
Garden Eel
Heteroconger · also called garden eels
Approach a garden eel colony too quickly and the whole swaying field disappears at once, hundreds of thin bodies vanishing straight down into the sand within seconds. Each eel spends essentially its entire life in that one burrow, extending just far enough to catch drifting plankton in the current and retreating the instant anything unfamiliar gets close.
Overview
The garden eel, genus Heteroconger, is a burrow-dwelling eel found on sandy slopes near coral reefs in tropical and subtropical oceans worldwide. Colonies of hundreds sway together in the current, feeding on plankton without ever fully leaving their burrows.
A field that grows underwater
Spaced consistently apart and swaying in unison to face the current, a large garden eel colony creates one of the reef’s more striking illusions, an entire “field” built from an animal that will likely never be seen fully out of the sand in its whole life.
Status
Least Concern — common and widespread across suitable sandy, current-swept habitat near reefs throughout tropical and subtropical oceans.
Garden Eel: common questions
Does a garden eel ever leave its burrow completely?
A garden eel spends essentially its entire life in the same burrow, extending the front portion of its body out to feed on drifting plankton and retreating fully inside at the slightest sign of danger, and it rarely if ever leaves the burrow completely, making it one of the more permanently burrow-bound fish species known.
Why do garden eel colonies look like a field of grass?
Garden eels typically live in dense colonies of hundreds of individuals, each in its own burrow spaced a consistent distance from its neighbours, and when the current causes many eels to sway together while facing into the flow to feed, the overall effect strikingly resembles a swaying field of grass or wheat on the sea floor.
How does a garden eel dig its burrow if it goes in tail-first?
A garden eel uses its pointed tail to wriggle backward into loose sand, gradually constructing a burrow tail-first rather than digging head-first as many other burrowing marine animals do, a method well suited to its long, thin, tapering body shape.
How do garden eels mate if they rarely leave their burrows?
Because garden eels are so reluctant to leave their burrows completely, mating typically occurs between neighbouring individuals that each stretch partway out of their own burrow toward each other, allowing reproduction to take place without either eel needing to fully abandon the safety of its burrow.