Spanish Dancer




Domain- EukaryaThe Spanish Dancer - Image courtesy to Chicka Wantanaba

Kingdom- Animalia

Phylum- Mollusca

Class- Gastropoda

Order- Nudibranchia

Family- Hexabranchidae

Genus- Hexabranchus

Species- Hexabranchus sanguineus

Domain – Eukarya: The Spanish Dancer is made up of eukaryotic cells which contain membrane bound organelles and a true nucleus, allowing it to fall under the category of eukarya. To learn about another intersting organism in this domain check out the Mantis Shrimp or the Tiger Flatworm!
Kingdom – Animalia: Animals are eukaryotic, multicellular organisms. They lack structural walls (cell wall which we see in plants) and are heterotrophic, meaning they must have some way of obtaining food since they cannot produce their own food like plants. Animals also require oxygen and are motile at some stage in their life. The Spanish Dancer belongs to the eukarya domain, meaning it is eukaryotic, and is also heterotropic as it is a carnivore and eats coral, sponges, and even other nudibranchs. Along with this, the Spanish Dancer is known for its mobility in the way that it swims. Interestingly enough, they are the only species of nudibranch that can swim. Other organisms that belong to this kindom are the Snow Crab and Japanese Puffer Fish.
Phylum – Mollusca: Members of the phylum Mollusca have a soft body that is usually protected by a shell (exoskeleton). They have a heart, digestive system, and nervous system. Other organisms in this category include snails such as the Dryland Liptooth, the Giant Pacific Octopus, the Humbolt Squid, clams, and oysters.
Class – Gastropoda: Gastorpod means “stomach foot” which describes the way the body and internal organs are arranged. Most organisms of the gastropoda class are hermaphrodites which means that they contain both male and female reproductive organs. This is true for the Spanish Dancer. Gastropods also use a radula to feed. A radula is a toungue-like structure that contains rows of teeth.  Gastropods also have a head with eyes and one or two pairs of tentacles. In the case of the Spanish Dancer, these tentacles are called rhinophores. Another cool example of an organism in this class is the Cinnamon Covert, the Upland Pillsnail, and the Whitelip Snail.
Order – Nudibranchia: This class contains numerous gastropod mollusks that lack a shell and have a soft body.
Family – Hexabranchidae: monotypic family of nudibranchs, or sea slugs, that are considered dorid and contain a single genus Hexabranchus.
Genus – Hexabranchus: This genus contains nudibranchs that appear redish-pink in colorand even yellow in rare form. They are also capable of swimming.
Species – Hexabranchus sanguineus: Here we have the Spanish Dancer nudibranch! Hexabranchus sanguineus translates to “blood colored six-gills.” This represents the six red colored gills of the nudibranch which are always exposed, or “naked."


Figure 1. Phylogeny of the animal phylums. This phylogeny was created by Devin Yurk.

This phylogeny shows where nudibranch place in the animal phylum. Following the red line leads you to the mollusca phylum where nudibranchs are categorized and from this we can see that they are close relatives to the annelida phylum.

The phylogeny below represents different spicule arrangement and characteristics among different species of nudibranchs. As we can see, the Hexabranchus sanguineus is most closely related to Bathydoris aioca, which share the common characteristics of absent spicules (Penney, 2008).



Figure 2. Phylogeny of spicule network characters. Higher taxa are based on that manuscript. Chromo. = Chromodorididae, Dorid. = Dorididae, Disco. = Discodorididae, Dendro. = Dendrodorididae, Phyll. = Phyllidiidae. Dashed line indicates division between the caryophyllid-bearing dorids and other Discodorididae. Missing boxes indicate characters not applicable to that species, ? = missing information. Characters are listed 1 to 5 vertically, as follows: 1. Spicule presence: 0 = present, 1 = absent. 2. Mantle edge network form: 0 = no network, 1 = dendritic, 2 = cobweb-like, 3 = lattice. 3. Central notum network: 0 = same as mantle edge, 1 = absent, 2 = large spicules. 4. Papillae support: 0 = no spicules, 1 = disorganized rosette, 2 = spicule ring, 3 = rods of large spicules. 5. Foot edge network form: 0 = no network, 1 = dendritic, 2 = cobweb-like, 3 = lattice.  This pylogeny was created by Angel Valdes.


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