- Sea butterfly
Taxobox
name = Sea butterflies
image_width = 200px
regnum =Animal ia
phylum =Mollusca
classis =Gastropoda
subclassis =Orthogastropoda
superordo =Heterobranchia
ordo =Opisthobranchia
subordo = Thecosomata
subordo_authority = Blainville, 1824
subdivision_ranks = Families
subdivision =Limacinidae Cavoliniidae Clioidae Creseidae Cuvierinidae Praecuvierinidae Peraclididae Cymbuliidae Desmopteridae Sea butterflies, also known as Thecosomata or flapping
snail s, are ataxonomic suborder ofpelagic swimming sea snails. These are holoplankton icopisthobranch gastropod mollusk s in the orderOpisthobranchia .This group used to be known as pteropods. This term, however, is no longer scientifically precise, but is still used sometimes as a convenience. The word pteropod applies both to the sea butterflies in the order
Thecosomata and also to the sea angels in the orderGymnosomata . Mollusks of the suborder Thecosomata have a shell, while the Gymnosomata lack a shell."Holoplanktonic" means that these snails spend their whole life in a planktonic form, rather than just being planktonic during the
larva l stage, as is more commonly the case in many marine gastropods.This is, geologically-speaking, rather a young group, having evolved from the Late
Paleocene in theCenozoic Era.Description and life habits
These snails float and swim freely in the water, and are carried along with the currents. This has led to a number of adaptations in their bodies. The shell and the
gill have disappeared in several families. Their foot has taken the form of two wing-like lobes, orparapodia , which propel this little animal through the sea by slow flapping movements. At times, they just float along,ventral -side up, with the currents. They are rather difficult to observe, since the shells are mostly colorless, very fragile and usually less than 1 cm in length. Theircalcareous shells are bilaterally symmetric and can vary widely in shape: coiled, needle-like, triangular, globulous.Little is known about the behaviour of sea butterflies, but they are known to have a peculiar way of feeding. They are mostly passive
plankton feeders, but at times they can be real hunters. They entangle planktonic food through amucous web that can be up to 5 cm wide, many times larger than themselves. If disturbed, they abandon the net and flap slowly away. When descending to deeper water, they hold their wings up. Sometimes, they swarm in large numbers and can be found washed up inflotsam especially along the coast of easternAustralia .Every day, they migrate vertically in the water column, following their planktonic prey. At night they hunt at the surface and return to deeper water in the morning.
Importance in the Food Chain
These creatures, which are about the size of a lentil, are eaten by various marine species, including a wide variety of fishes that are, in turn, consumed by penguins and polar bears. Researcher Gretchen Hofmann, calls them the "potato chip" of the ocean. She says that as the ocean becomes more acidic and warmer, these creatures are not able to survive. "It's possible by 2050 they may not be able to make a shell anymore. If we lose these organisms, the impact on the food chain will be catastrophic." [Climate Change Seen Turning Seas Acidic, 93106, March 3, 2008, University of California Santa Barbara.]
Popular culture
Sea butterflies make an appearance in the
video game , where they may be caught in the ocean.Taxonomy
Ponder & Lindberg
Order Thecosomata
de Blainville , 1824
* InfraorderEuthecosomata
** SuperfamilyLimacinoidea
*** FamilyLimacinidae de Blainville , 1823
** SuperfamilyCavolinioidea
*** FamilyCavoliniidae H. and A. Adams, 1854
*** FamilyClioidae
*** FamilyCreseidae
*** FamilyCuvierinidae
*** FamilyPraecuvierinidae
* InfraorderPseudothecosomata
** SuperfamilyPeraclidoidea
*** FamilyPeraclidae Tesch, 1913
** SuperfamilyCymbulioidea
*** FamilyCymbuliidae Gray, 1840
*** FamilyDesmopteridae Dall, 1921Bouchet & Rocroi
In the new taxonomy of Bouchet & Rocroi (2005) Thecosomata is treated differently :
The superfamily Limacinoidea becomes redundant and the family Limacinidae becomes part of the superfamily Cavolinioidea. The families Creseidae and Cuvierinidae become the subfamilies Creseinae and Cuvierininae. The infraorder Pseudothecosomata becomes the superfamily Cymbulioidea. The superfamily Peraclidoidea becomes redundant and the family Peraclididae is included in the superfamily Cymbulioidea as the family Peraclidae.
Notes
References
* A.W.H. Bé and R.W. Gilmer. 1977. A zoogeographic and taxonomic review of euthecosomatous pteropoda. Pp. 733-808 In: Oceanic Micropaleontology, Vol. 1. A.T.S. Ramsey (ed.). Academic Press, London.
* S. van der Spoel, 1967. Euthecosomata, a group with remarkable developmental stages (Gastropoda, Pteropoda). Gorinchem (J. Noorduijn)(thesis University of Amsterdam):375 pp., 17 tabs, 366 figs
* S. van der Spoel, 1976. Pseudothecosomata, Gymnosomata and Heteropoda (Gastropoda). Utrecht (Bohn, Scheltema & Holkema): 484 pp., 246 figs.
* Cainozoic Research, 2(1-2): 163-170, 2003: regarding the raising of ranks.ee also
*
Ocean acidification
* [http://www.tafi.org.au/zooplankton/imagekey/mollusca/pteropod.html Pteropoda Fact Sheet]
Wikimedia Foundation. 2010.