Sea lilies
Classis Crinoidea Miller, 1821

   It is not without reason that sea lilies have received their name: outwardly they are indeed reminiscent of a pennibranched flower.  Their body consists of a cup (central cone) and radial articulated arms (feelers) with side branches, pinnulae. Sea lilies are the sole recent echinoderms that have retained the body orientation characteristic of their echinoderm ancestors: the mouth is turned upwards, and the animals dorsal side is turned to the soil surface. An articulated attachment pedicel with a cluster of attachment outgrowthscirruses or, like in stemless, a cluster of cirruses branches directly from the cup. There may be little teeth or claws on the cirrus ends, with which the lily securely fastens itself to the substrate.
   Like in all Echinodermata, it, body structure  is subordinate to radial five=ray symmetry. It always has five arms; however, they may repeatedly separate to produce from 10 to 200 false arms with numerous side pinnulae, forming a dense catch network. The feelers surrounding the mouth have mucous-ciliary ambulacral grooves, along which food particles captured from water depths are transported to the oral cavity. The latter is situated I the middle of the upper (abdominal) cup surface, to which five ambulacral grooves converge from the arms. The anal opening is also situated alongside on the apex of a special papilla. With regard to feeding habits, sea lilies eat microplankton.
   Apart from their external form and orientation of dorsal-abdominal body axis, sea lilies are distinuished from other echinoderms by a slightly simplified ambulacral system: they have neither leg-controlling ampoules, nor madrepore plates.
 Stemless lilies can detach from the substrate and move along the sea floor, and even surface by moving their arms.
 The plankton larva of sea lilies is called vitellaria.
   After metamorphosis, the larva takes a miniature stalk-like semblance of an adult animal. The pedicel disappears in stemless lilies as they become adults.
   Six hundred and twenty five lily species are known to exist, most of them inhabiting tropical waters or at great depths. One species occurs in Southern Primorye, (1) Heliometra glacialis (Leach, 1815)


Sea lily (comatulid) cup from top (abdominal side). Abambulacral groove; Aanal cone; Brays; Mmouth; Ppinnulae (according to Roehler).