Macrodasys caudatus is a species of microscopic worm-like metazoan in the family Macrodasyidae in the phylum Gastrotricha.

[1] The body is worm-shaped with small adhesive tubes (spine-like structures) on the lateral sides.

[2] Macrodasys caudatus is an aquatic, microscopic worm with a body length of 0.06–3.0 millimetres (0.0024–0.1181 in).

Macrodasys caudatus is acoelomate and swallows its food by powerful sucking action of the muscular pharynx.

Recent phylogenetic studies based on gene 18S ribosomalt RNA and expressed sequence tag (EST), indicate that Gastrotricha is a member of platyzoa.