Animal profile

Placozoan

Trichoplax adhaerens

PlacozoaWarm shallow marine environments, often found on aquarium glass and hard substrates

Field profile

A flat, amoeba-like animal roughly a millimetre across with no mouth, gut, nerves, muscles or fixed body shape. It consists of a few cell types arranged in two epithelial layers. It was described in 1883 from an aquarium in Graz.

Published field notes

2026-07-22

Placozoan

The placozoan is an animal without organs

Trichoplax has no mouth, gut, nerves, muscles or symmetry. It is a flat sheet of a handful of cell types that crawls over surfaces and digests food by pressing its underside against it.

Read with evidence →