Glaucidae

Glaucidae
	Glaucus atlanticus (left) and Glaucus marginatus (right)
Systematics
Superordinate :	Heterobranchia
Order :	Hind gill snails (Opisthobranchia)
Subordination :	Nudibranchia (Nudibranchia)
Partial order :	Thread snails (Aeolidida)
Superfamily :	Aeolidioidea
Family :	Glaucidae
Scientific name
	Glaucidae
	Gray , 1827

The Glaucidae are a family of thread snails in the suborder of the nudibranchs . It consists of the two pelagic snail species Glaucus atlanticus and Glaucus marginatus (also Glaucilla marginata ), which swim around the world in warm and temperate seas , which eat cnidarians living on the sea surface .

features

In adaptation to the pelagic way of life, the Glaucidae have a flattened body with 3 to 4 pairs of lateral "feet" (pedunculi) on which the long cerata sit, which stabilize the position of the snail in the water. The animals have a small head with protruding eyes, a pair of short mouth feelers and above two very short, barely visible rhinophores . As with other thread snails, extensions of the midgut gland lead into the Cerata , which end in so-called nettle sacs. This is where the nettle capsules of the nettles they eat are stored and serve to defend the snails against predators.

The teeth of the single-row radula have a protruding cusp, which is comparatively longer in Glaucus marginatus than in Glaucus atlanticus , and a series of small teeth. The strong jaws are chitinous . The anus opens laterally on the back between the second and third pedunculus, the nephridium also on the back between the first and second pedunculus.

Like other thread snails, the Glaucidae are hermaphrodites . The female genital opening is on the right of the abdomen. The penis, reinforced with a chitin spike, is longer than the body of the snail and thus enables two swimming snails to mate with each other. The eggs are attached to drifting prey remains or seaweed in egg strings. Numerous Veliger larvae with a small shell hatch from the eggs, feed on plankton and finally metamorphose into small shell-less snails .

The glaucidae eat pelagic Hydrozoen ( sailing and siphonophores , Porpita Porpita ). While Glaucus atlanticus reaches lengths of 4 cm, Glaucus marginatus is only a few millimeters in size.

Systematics

According to Bouchet and Rocroi (2005), the Glaucidae family is one of four families in the superfamily Aeolidioidea . There are two types of family:

Glaucus atlanticus Forster, 1777
Glaucus marginatus (Bergh, 1860), synonym: Glaucilla marginata Bergh, 1860

The two species traditionally belong to the two monotypical genera Glaucus Forster, 1777 and Glaucilla Bergh, 1860, but because of their great similarity, they put Valdés and Campillo in a common genus Glaucus in 2004 , so that the Glaucidae are now a monogeneric family.

On the basis of a work by Michael Miller from 1974, the term of the family Glaucidae was for a time understood by some authors to a much larger extent, including the postulated subfamilies Facelininae, Favorininae, Crateninae and Herviellinae (previous families Babainidae , Facelinidae and Favorinidae ) and thus included also numerous benthic genera, including Facelina , Dondice and Hermissenda . This proposal was always controversial and was rejected, among other things, with the argument that the subfamilies were polyphyletic and that the two species Glaucus atlanticus and Glaucilla marginata deserved the status of a separate family because of their highly specialized pelagic way of life. According to the system of Bouchet and Rocroi (2005), the benthic species that are temporarily included under Glaucidae belong to the Facelinidae family.

literature

Carol M. Lalli and Ronald W. Gilmer: Pelagic Snails: The Biology of Holoplanktonic Gastropod Mollusks. 259 S., Stanford, Calif., Stanford Univ. Pr., 1989 ISBN 0-8047-1490-8
Adam Sedgwick, Joseph Jackson Lister, Sir Arthur Everett Shipley: A Student's Text-book of Zoology: Protozoa to Chaetognatha . S. Sonnenschein and Company, 1898. Glaucidae : p. 412.
Philippe Bouchet & Jean-Pierre Rocroi: Part 2. Working classification of the Gastropoda . Malacologia, 47: 239-283, Ann Arbor 2005 ISSN 0076-2997
A. Valdés, OA Campillo (2004): Systematics of pelagic aeolid nudibranchs of the family Glaucidae (Mollusca, Gastropoda) . Bulletin of Marine Science 75 (3), pp. 381-389.

Web links

Commons : Glaucidae - Collection of images, videos, and audio files

Sea Slug Forum (Australian Museum, Sydney): Glaucus atlanticus and Glaucilla marginata

Individual evidence

^ World Register of Marine Species , Glaucidae Gray, 1827 , Glaucus Forster, 1777
↑ Michael C. Miller (1974): Aeolid nudibranchs (Gastropoda: Opisthobranchia) of the family Glaucidae from New Zealand waters . Zoological Journal of the Linnean Society 54 (1), pp. 31-61.
↑ This system can still be seen, for example, on Taxonomy Browser: Glaucidae , National Center for Biotechnology Information (NCBI), National Institutes of Health, US Department of Health and Human Services. Accessed November 10, 2012.
^ Luise Schmekel, Adolf Portmann: Opisthobranchia of the Mediterranean: Nudibranchia and Saccoglossa . Springer-Verlag, Berlin Heidelberg New York 1982. p. 198.

[WoRMS-1] World Register of Marine Species , Glaucidae Gray, 1827 , Glaucus Forster, 1777

[2] Michael C. Miller (1974): Aeolid nudibranchs (Gastropoda: Opisthobranchia) of the family Glaucidae from New Zealand waters . Zoological Journal of the Linnean Society 54 (1), pp. 31-61.

[3] This system can still be seen, for example, on Taxonomy Browser: Glaucidae , National Center for Biotechnology Information (NCBI), National Institutes of Health, US Department of Health and Human Services. Accessed November 10, 2012.

[4] Luise Schmekel, Adolf Portmann: Opisthobranchia of the Mediterranean: Nudibranchia and Saccoglossa . Springer-Verlag, Berlin Heidelberg New York 1982. p. 198.