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Marine Animal Encyclopedia

Mud Dragon Echinoderes aquilonius

Mud dragons look rather like miniature insect pupae. The body appears segmented on the outside but this is only superficial. It is covered with a thick, articulated cuticle and there are sharp spines on each body section. The tail end has a bunch of longer spines, and the head region has several rings of spines. The mouth is situated on the end of a cone-shaped structure and the animal can withdraw the entire head region into the rest of the body for protection rather as a tortoise does, but it can also close the resulting hole with special plates, which are called placids. The head spines are used to help the animal push its way through the sediment, feeding on organic debris, bacteria, protists, and diatoms.

There are about 100–150 species of mud dragons, all of which are marine. The sexes are separate but look similar. The eggs develop into free-living larvae that molt several times before attaining the adult form.

  • Phylum Kinorhyncha
  • Length Less than 1 mm
  • Depth Shallow water
  • Habitat Muddy sediments
  • Distribution Northwestern Atlantic