Apodida

{{Short description|Order of sea cucumbers}} {{Automatic taxobox | image = Euapta godeffroyi1.jpg | image_caption = ''Euapta godeffroyi'' | taxon = Apodida | subdivision = * †Achistridae * Chiridotidae * Myriotrochidae * Synaptidae | synonyms = * Apoda [Variant spelling] * Synaptida }}

'''Apodida''' is an order of littoral to deep-sea, largely infaunal holothurians, sea cucumbers. This order comprises three families, 32 genera and about 270 known species, called '''apodids''', "without feet".

==Characteristics== These sea cucumbers are vagile holothurians with an elongated shape (up to 3 meters for ''Synapta maculata''), worm or snake-like. Their shape is adapted for burrowing through the sediment, sometimes in a fashion similar to earthworms. Their mouth is surrounded with 10-25 pinnate or peltate tentacles. The absence of tube feet gives the order its name, ''Apodida'' meaning ''without feet'' : they move by crawling on the sediment, hence they need flat bottoms with few current. Members of this order have a circum-oral ring and tentacles, but do not have tube feet or radial canals. They also lack the complex respiratory trees found in other sea cucumbers, and respire and excrete nitrogenous waste through their skin.<ref>{{cite book |author= Barnes, Robert D. |year=1982 |title= Invertebrate Zoology |publisher= Holt-Saunders International |location= Philadelphia, PA|pages= 981–996|isbn= 0-03-056747-5}}</ref>

The ossicles, minute calcareous plates embedded in the skin and characteristic of each species, can include wheel and anchor shapes.<ref>[http://www.dnr.sc.gov/marine/sertc/Sea_Cucumber_key.pdf An illustrated key to the sea cucumbers of the South Atlantic Bight] Retrieved 2012-02-12.</ref>

== List of families == This order contains 3 extant families, consisting in 32 genera in total, for 270 known species.{{Citation needed|date=August 2025}} * family Chiridotidae Östergren, 1898 * family Myriotrochidae Théel, 1877 * family Synaptidae Burmeister, 1837 * family †Achistridae Frizzell and Exline, 1955

{{clr}} <gallery style="text-align:center;" mode="packed"> File:Chiridota heheva.jpg|''Chiridota hydrothermica'' File:Polycheira rufescens.JPG|''Polycheira rufescens'' File:Euapta godeffroi.jpg|''Euapta godeffroyi'' File:Euapta lappa.jpg|''Euapta lappa'' File:Polyplectana kefersteinii.jpg|''Polyplectana kefersteinii'' File:Synapta maculata 2.jpg|''Synapta maculata'' File:Synaptula lamperti (Sea cucumber).jpg|''Synaptula lamperti'' </gallery>

==References== {{Reflist}}

Category:Apodida Category:Echinoderm orders