Pterotracheoidea
Pelagic worm Pterotracheidae the family. Links of the trunk, above the Flipper, right of the visceral core
The Kielfüßer or Pterotracheoidea are a superfamily of gastropods which have a pelagic life. All forms are predators. They had earlier discovered the status of an order, and were referred to as Heteropoda or Heteropods. The oldest representatives of Pterotracheoidea known from the Lower Jurassic ( Toarcian ).
Features
The group includes very large (about 50 cm) to small shapes (about 1 cm). The soft body is gelatinous and translucent. The animals swim with the help of the converted into a fin on the back foot. The case is, if still present thin and fragile; it is even regressed completely in a family. The original shell bearings forms can still withdraw completely into the housing even.
In adaptation to the pelagic snails lens eyes have a large spherical lens and a band-shaped retina. The mouth is located at the end of a movable proboscis extension of the head ( proboscis ). The radula bears on the edge elongated, sickle -shaped teeth which serve to capture prey.
The animals are dioecious. The males transmit the seed packets with the help of a long penis into the mantle cavity of the female. The development proceeds through a plankton -feeding veliger larva. The larva forms a Larvalgehäuse that can be closed with an operculum. In the species of the family the Larvalgehäuse and the operculum is shed during metamorphosis. The types of Carinariidae retain the housing, but throw off the operculum. The types of Atlantidae family housing and operculum will keep for life.
Lifestyle and diet
The representatives of the superfamily live and feed on pelagic prey on other animals of the plankton (or nekton ). The prey is either decomposed with the radula or swallowed whole.
Occurrence
The species of the superfamily live worldwide in the upper 200 meters of the warmer seas. They are usually not very common.
System
Currently three families are made to this superfamily:
- Rafinesque - Schmaltz Pterotracheidae, 1814
- Carinariidae Blainville, 1818
- Atlantidae Rank, 1829
Jean -Baptiste de Lamarck described the group in 1812 under the name Heteropoda as the fifth of five Sections within the order of " head -bearing mollusks ." Later, they were viewed as an order within the worm scientifically called so. As it is now downgraded to a superfamily and only generic based name for superfamilies are allowed, today only the 1814 award of Constantine S. Rafinesque - Schmaltz name Pterotracheoidea valid. Another commonly used synonym is Carinarioidea. The name Heteropoda today is only valid for a genus of giant crab spiders.