{"id":7852,"date":"2013-09-10T12:55:08","date_gmt":"2013-09-10T10:55:08","guid":{"rendered":"https:\/\/opistobranquis.info\/pleurobranchomorphapleurobranchomorphapleurobranchomorpha"},"modified":"2025-10-29T16:21:53","modified_gmt":"2025-10-29T15:21:53","slug":"pleurobranchida","status":"publish","type":"page","link":"https:\/\/opistobranquis.info\/en\/guia\/pleurobranchida\/","title":{"rendered":"Pleurobranchida"},"content":{"rendered":"

The pleurobranchids have a fairly homogeneous body organization, highlighted by the presence of a voluminous bipectinate gill to the right of the body, between the foot and the dorsal mantle. In fact the name of the group is related to this organ’s position (Pleurobranchid = gill aside).<\/p>\n

\"Berthella<\/div>
Berthella aurantiaca<\/em> by Enric Madrenas<\/center><\/span>

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Animals are medium to large size. The head has a pair of rolled rhinophores and a flattened frontal veil that usually differentiates short oral tentacles. The dorsal mantle is well developed and can be smooth or covered with tubercules, and completely covers the body. In the genus Pleurobranchus <\/em>and Berthella <\/em> the shell is internal as it is covered by the mantle, while the Pleurobranchaea lack any shell. In some species there are microscopic spicules in the mantle. The buccal bulb has a lip with masticatory independent elements and the radula always exist but has no rachideal or medium tooth . The mantle cavity is a kind of narrow groove between the mantle and the foot on the right side of the body and holds the gill. The foot is very large, allowing swimming in some species, such as Pleurobranchus membranaceus<\/em>, and in the back it has an apparent metapodial mucus-secreting gland.<\/p>\n

Biology
\n<\/strong>Some species of pleurobranchids are big sized (about 20 cm for the largest specimens of Pleurobranchus testudinarius<\/em> and Bathyberthella antarctica<\/em>) and use to be very visible on their habitats. They are usually very sedentary and many, as the species of the genus Berthella<\/em>, live under the stones on the seabed, even at very shallow depths. Some species of the Pleurobranchidae family may swim with undulating movements of the edge of the mantle and the foot. They are hermaphrodites, have internal fertilization, and copula is reciprocal. Shortly after mating, the animals lay a straight or spiral coiled ribbon containing from one to 30 egg capsules, deppending on the species. Veliger <\/em>larvae that hatch from the eggs are planktonic and planktotrophic (feed on plankton). They are carnivorous and can feed on sponges, colonial or solitary tunicates and other invertebrates. Pleurobranchaea meckeli<\/em> could prey on smaller specimens of the same species, in laboratory conditions. Many species are able to release acid substances from the mantle glands when disturbed by a potential predator or under experimental conditions.<\/p>\n

Distribution
\n<\/strong>Most species live in temperate and tropical waters of all oceans. Known species (4) of the genus Bathyberthella <\/em>live in the deep and cold waters of the Southern Hemisphere and Antarctica oceans. Several species have been cited in European waters, most of them are also found in Iberian waters .<\/p>\n

Classification
\n<\/strong>Formerly known as Pleurobranchomorpha, this group belonged, until recently, to the traditional order of Notaspideans within the Opisthobranchia, which is no longer accepted. This is because, as it has been recently demostrated, comparative morphological analysis and molecular studies, the two included families (Pleurobranchidae <\/em>and Umbraculidae<\/em>) represent two different lineages that may not share common ancestors. Phylogenetic analysis conducted in recent years tend to place the Pleurobranchida <\/em>as the sister group of the Nudibranchia , forming with them a group with the category of Superorder called Nudipleura .<\/p>\n

The taxonomy of this group according to Bouchet et al. (2017) and published at WoRMS is as follows:<\/p>\n

Pleurobranchida<\/strong><\/p>\n