The Echinothuriidae are a family of
sea urchins in the order
Echinothurioida
The Echinothurioida are an order of sea urchins in the class Echinoidea. Echinothurioids are distinguished from other sea urchins by the combination of a flexible test and hollow spines. The membrane around the mouth contains only simple plat ...
.
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.
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'').
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.
This family seems to have appeared at the end of the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
.
Taxonomy
The World Echinoidea Database recognises these genera:
[Kroh, A. (2015)]
Echinothuriidae Thomson, 1872
In: Kroh, A. & Mooi, R. (2015) World Echinoidea Database.
* 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
In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...
.
Image:Araeosoma thetidis insitu.tif, '' Araeosoma thetidis'' (New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
, 188 m depth)
Image:Toxic Leather Sea Urchin - Asthenosoma marisrubri.jpg, '' Asthenosoma marisrubri''
Image:Deep sea Echinothurioid.jpg, '' Hygrosoma'' sp. (abyssal species from north Atlantic)
Image:Sperosoma.jpg, '' Sperosoma'' sp. (abyssal species taken in Hawaii)
Image:Expl0867 - Flickr - NOAA Photo Library.jpg, '' Tromikosoma'' sp. (3000 m deep, California)
References
{{Taxonbar, from=Q1132966
Extant Middle Jurassic first appearances