''Petalifera'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

sea slug Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails (marine gastropod mollusks) that over evolutionary t ...

s or sea hares,

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

s belonging to the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Aplysiidae Aplysiidae is the only family in the superfamily Aplysioidea, within the clade Anaspidea. These animals are commonly called sea hares because, unlike most sea slugs, they are often quite large, and when they are underwater, their rounded body sh ...

, the sea hares. Some authors place this genus in a separate family Dolabriferidae. A new study, published in September 2004, has shown that the genus ''Petalifera'' is

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

. (Note: Gastropod

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

has been in flux for more than half a century, and this is especially true currently, because of new research in

molecular A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

. Because of all the ongoing changes, different reliable sources can yield very different classifications.) A more general description can be found on the page of the superfamily Aplysioidea.

Description

The

parapodia In invertebrates, the term parapodium ( Gr. ''para'', beyond or beside + ''podia'', feet; plural: parapodia) refers to lateral outgrowths or protrusions from the body. Parapodia are predominantly found in annelids, where they are paired, unjointed ...

(fleshy winglike outgrowths), as can be seen in photos of ''Petalifera petalifera'', are almost completely fused. The pair of small rounded flaps form the parapodial cavity over the

mantle A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that. Mantle may refer to: *Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear **Mantle (vesture), an Eastern Orthodox ve ...

cavity and the vestigial shell. These sea hares swim by coiling and uncoiling the body.

Species

*'' Petalifera albomaculata'' Farran, 1905 -

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

. *'' Petalifera habei'' Eales, 1960 (synonym of ''Petalifera ramosa'') *'' Petalifera krusadalai'' O’Donoghue, 1930 *''

Petalifera petalifera ''Petalifera'' is a genus of sea slugs or sea hares, marine gastropod mollusks belonging to the family Aplysiidae, the sea hares. Some authors place this genus in a separate family Dolabriferidae. A new study, published in September 2004, has ...

'' Rang, 1828Rang S. (1828). Histoire Naturelle des Aplysiens. Paris, Firmin Didot 83 pp., 24 pl. **Distribution : Cosmopolitan. **Length : 2 to 4 cm **Color : grayish to brown, with white longitudinal bands; almost translucent. **Description : rather flat body; their color camouflages them when they are grazing on the brown alga '' Padina''. *'' Petalifera punctulata'' Tapparone-Canefri, 1874 **Distribution :

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

*'' Petalifera qingdaonensis'' Lin, 1990 *'' Petalifera ramosa'' Baba, 1959 **Distribution : Western Pacific,

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

. **Length : 5 to 7 cm **Color : pink to pale brownish, with white rings over the body; almost translucent. **Description : mantle covered with firm conical tubercles; the larger tubercles have terminal papillae with retractable filamentous branches; difficult to find, mostly hidden under the leaves of green alga '' Caulerpa''.

Footnotes

External links and references

* *
Photo of ''Petalifera petalifera''

{{Taxonbar, from=Q3169109 Aplysiidae Taxa named by John Edward Gray Gastropod genera