Cerata

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Cerata ( singl. ceras, AltGr. Ἡ κεραία ( keraia ) = Horn, AltGr. Κερας ( keras ) = -horn, antler ) are skin appendages, sea snails or marine opisthobranch on her back ( dorsal) or on the sides ( lateral) form.

Function

Cerata are skin growths that increase the skin surface of the animals. Since the necessary for cell metabolism gas exchange (CO2 against O2) depends on the number of available specialized cells on the surface, will enhance and improve breathing through the Cerata.

In the picture you can see the Cerata of Fiona pinnata. Inside the Cerata are located on the front strongly fanned membranes. These membranes are bundled in small, after under running vessels which run the Cerata out into a larger center strand.

Some snails group within the nudibranchs that Cerata be covered by a thin, central papillary. This includes the Cerata on to the digestive tract. Thus can be a solute transport in and out of the Cerata, and the Cerata can take over secondary functions in addition to its main function ( respiratory support ).

In the picture on the left ( Janolus fuscus ) you can clearly see the dark papillary in the center and three sections of the Cerata: a bright ground floor, a yellow top with nematocysts, and the Cerataspitzen.

Most thread worm feed on cnidarians ( Cnidaria ) and nematocysts which can accommodate ( nematocytes ) safely. But instead of digesting them, they are unscathed in the tensioned state in particular, which opens to the outside skin bags ( Nettle bags) stored at the tips of Cerata. In dangerous situations, or fractures of the Cerataspitzen the nettles are then shot down over nettle channels. Since the nematocysts are not developed in -house production, these animals are also called nettle thieves ( Kleptocnide ).

Other groups such as Breitfußschnecken the genus Aplysia, also known as sea hares, use the Cerata Glare tactics. The Aplysia can not actively defend using nematocysts, but they store in their Cerata unpleasant-smelling secretions. However, since they come (just like lizards their tails ) from one or more of the Cerata. These remain and contract strongly for some time. At the same flows from the smelly secretion and leaves in the water a white to purple cloud. The calculus of such tactics is that potential attackers are irritated by the contracting Cerata or distributing dyes, or are repelled by smelly secretions and thus escape time is obtained.