Echinothuriidae

The Echinothuriidae are a family of sea urchins in the order Echinothurioida. Due to their soft skeletons, most are called "leather urchins", but species in the genus Asthenosoma are also known as "fire urchins" due to their bright colors and painful, venomous sting.

Echinothuriidae
Temporal range: Middle Jurassic–Recent
Fire urchin (Asthenosoma varium)
Scientific classification
Kingdom:
Animalia
Phylum:
Echinodermata
Class:
Echinoidea
Subclass:
Euechinoidea
Superorder:
Diadematacia
Order:
Echinothurioida
Family:
Echinothuriidae

(Thomson, 1872)
Genera
See text

Description and characteristics

These sea urchins have a disc-like body, more or less bulging, structured by a flexible test, which is nearly unique among sea urchins. Most species can grow quite big and live in deep seas, though some genera contain shallow species (especially Asthenosoma).[1]

The test is composed of thin and weakly calcified plates, not always continuous. The spines are attached to perforated and uncrenulated tubercles. Spines from the oral face are ending with a hyaline hoof, which allows walking on soft substrate. The jaw (Aristotle's lantern) has five aulodont teeth.[2]

This family seems to have appeared at the end of the Cretaceous.[2]

Taxonomy

The World Echinoidea Database recognises these genera:[3]

  • Subfamily Echinothuriinae Thomson, 1872a
    • genus Araeosoma Mortensen, 1903b - 19 current species and two fossils
    • genus Asthenosoma Grube, 1868 - six current species and one fossil
    • genus Calveriosoma Mortensen, 1934 - two species
    • genus Hapalosoma Mortensen, 1903b - four species
  • Sub-family Hygrosomatinae Smith & Wright, 1990
    • genus Hygrosoma Mortensen, 1903b - three species
  • Sub-family Sperosomatinae Smith & Wright, 1990
    • genus Sperosoma Koehler, 1897 - 11 species
    • genus Tromikosoma Mortensen, 1903 - six species
  • genus Retzneiosoma Kroh, 2005 †

"†" means an extinct taxon.

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References
  1. Mah, Christopher L. "What are the Deepest known echinoderms ?". The Echinoblog.
  2. "Echinothuriidae". Echinoid Directory.
  3. Kroh, A. (2015), Echinothuriidae Thomson, 1872, In: Kroh, A. & Mooi, R. (2015) World Echinoidea Database.
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