Hypselodoris bullocki
Blue Dorid [+]
Description & Behavior
The blue dorid nudibranch, Hypselodoris bullocki (Collingwood, 1881), ranges in color from a pale straw, or even white background to a deep purplish pink. There is usually a thin opaque white line at the mantle border, but some have a reddish purple border. Typically the gills and rhinophores are yellow or orange with a basal pink or purplish band. Unpublished studies of the anatomy show that this species should probably be placed in the genus Risbecia.
There are four basic types of nudibranchs: Doridoidea, Aeolidoidea, Dendronotoidea, and Arminoidea. Doridoidea and Aeolidoidea are the two largest suborders of nudibranchs. Characteristics of Doridoidea include a broad, flat foot, a thick, fleshy mantle, and a circle of gills on the posterior end of the dorsal surface. The gill surrounds the anus. These nudibranchs are also generally the larger species. Aeolidoidea have long, narrow bodies, lack gills, and have a number of projections on the dorsum called cerata. These slugs are generally smaller in size. Dendronotoidea characteristics include rhinophoral sheaths, mid-lateral anus, but resemble aeolid's. Finally, Arminoidea is made up of a motley group of species. The species in this suborder differ amongst themselves which makes very few externally consistent characteristics. Some features that many of the species in this suborder share are lack of rhinophoral sheaths and, often, oral tentacles, and the anus is far forward on the body. These broad characteristics of the suborders are helpful in determining which suborder an individual belongs to so that it may be identified further.
Nudibranchs move by muscular action or by ciliary action which causes the slug to move quite slowly. In a slug that moves via muscular action, contraction and expansion of the muscles move the slug forward. In ciliary motion, cilia in the foot beat against the substrate causing the slug to move forward.
World Range & Habitat
Originally described from the South China Sea, this species is found in the western Pacific as far south as southern Queensland. It is also found in north western Australia, Thailand, the tropical western Pacific, and the eastern Indian Ocean.
Feeding Behavior (Ecology)
All nudibranchs are carnivorous feeding on sessile or sedentary organisms. Each suborder of nudibranch has a major food source. For dorids, most food comes from preying on bryozoans and sponges (Dysidea and Aplysilla) while aeolid's and dendronotaceans prey upon cnidarian species. Just as the suborder Arminacea is diverse, so is the food they consume. It is important to remember that the substrate a nudibranch is found on may not necessarily be its food source.
Life History
All nudibranchs are hermaphroditic, but rarely will they fertilize themselves. Normally nudibranchs will copulate and each individual will lay an egg mass, called a nidosome. Egg masses of a number of nudibranchs are quite distinctive and can be found on substrates where nudibranchs feed or are often found. When the eggs hatch, a veliger larva (larva with a protective shell and a ciliated flap-shaped foot used for swimming and feeding) is usually released. The veliger has a shell, but once the larvae has settled out of the plankton, the shell is released and they enter a juvenile stage.
Conservation Status/Additional Comments
Very delicate and fussy feeders. Not recommended for aquaria. Nudibranchs are a diverse group of species and are found throughout the world. Little is known about them due to their short life span and the fact that they often appear in one place and disappear shortly after making it difficult to study the ecology and life history of the organisms. The Pacific Coast, and particularly Monterrey Bay, has a large number of species of nudibranchs compared to other areas of the world where these animals are found.
References & Further Research
BioOne ~ CITES ~ Discover Life ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList ~ MarineBio Network ~ NCBI ~ SCIRIS ~ SIRIS ~ Tree of Life Web Project ~ Wikipedia
The Slug Site
Hypselodoris bullocki (Collingwood, 1881)
Jeff's Nudibranch Site and Coral Reef Gallery
The Slug Site
Nudibranchs of Eastern Australia (South Qld and NSW), Lady Musgrave Island, Thailand, Red Sea, and Australian Flatworms
Sea Slug Forum
OKINAWAN OPISTHOBRANCH OF THE WEEK
Search the Web for Blue Dorid » ARKive ~ Ask.com ~ Ask Jeeves ~ bing ~ deviantART ~ dmoz ~ Dogpile ~ Google Images ~ MySpace Images ~ OceanFootage ~ Picsearch ~ StumbleUpon ~ Yahoo! Images ~ YouTube
