33 named species are placed in this genus at present, but at least two additional undescribed ones are known to exist, while some of the described ones are known only from a few specimens or (e.g. the enigmatic Chondrocladia occulta) just a single one, and their validity and/or placement in Chondrocladia is doubtful. Chondrocladia sponges are stipitate, with a stalk frequently anchored in the substrate by rhizoids and an egg-shaped body, sometimes with branches that end in inflatable spheres.[5][6]
Fossils assignable to this genus are known since the Pleistocene,[7] less than 2 million years ago. But given its deep seahabitat, Chondrocladia may well have been around for much longer – perhaps since the Mesozoic, as characteristic spicules (termed "microcricorhabds" or "trochirhabds"), almost identical to those of some living Chondrocladia, are known from Early Jurassic rocks almost 200 million years old.[6]
Carnivory
These sponges gained media attention when a new species, a gourd-shaped carnivorous sponge, was featured in reports of finds off the coast of Antarctica. The new Chondrocladia was one of 76[citation needed] sponge species identified in the seas off Antarctica by the Antarctic Benthic Deep-Sea Biodiversity Project (ANDEEP) between 2002 and 2005, conducted aboard the German research vessel Polarstern.[8][9]
Carnivorous sponges, which use hooked spicules to capture small crustaceans, have been known only since 1995, when Asbestopluma hypogea, another genus of the family Cladorhizidae, was identified in Mediterranean sea caves offshore La Ciotat (France) by Jean Vacelet and Nicole Boury-Esnault.[10] Carnivory has since turned out to be common and typical for this sponge family.[11][4] Unlike their relatives, Chondrocladia still possesses the water flow system and choanocytes typical of sponges, albeit highly modified to inflate balloon-like structures that are used for capturing prey.[4][6]
^* Vacelet, J. (2006). New carnivorous sponges (Porifera, Poecilosclerida) collected from crewed submersibles in the deep Pacific. Zoological Journal of the Linnean Society148: 553–584. Figure 17. doi:10.1111/j.1096-3642.2006.00234.x
^Van Soest, R. W. M., Boury-Esnault, N., Vacelet, J., Dohrmann, M., Erpenbeck, D., De Voogd, N. J., Santodomingo, N., Vanhoorne, B., Kelly, M., Hooper, J. N. A. (2011). Global Diversity of Sponges (Porifera). PLoS ONE7(4): e35105. Figure 3. doi:10.1371/journal.pone.0035105
^ abcdevan Soest, R. (2014). Van Soest RW, Boury-Esnault N, Hooper JN, Rützler K, de Voogd NJ, de Glasby BA, Hajdu E, Pisera AB, Manconi R, Schoenberg C, Janussen D, Tabachnick KR, Klautau M, Picton B, Kelly M, Vacelet J (eds.). "Chondrocladia Thomson, 1873". World Porifera database. World Register of Marine Species. Retrieved 2014-04-30.
^ abCristobo, Francisco Javier; Urgorri, Victoriano; Ríos, Pilar (2005). "Three new species of carnivorous deep-sea sponges from the DIVA-1 expedition in the Angola Basin (South Atlantic)". Organisms Diversity & Evolution. 5 (Supplement 1): 203–213. doi:10.1016/j.ode.2004.11.004.