Creature 319: Astropecten articulatus

Easy one

I have been publishing a lot of lazy posts lately because I am very close to submitting my PhD thesis. Today is no exception.

Astropecten articulatus is a fairly common but cool looking Starfish.

Distribution:
Astropecten articulatus can be found in the Carribean and along the East coast of the United States and South America as far south as Brazil.

Classification:
Kingdom: Animalia
Phylum: Echinodermata
Class: Asteroidea
Order: Paxillosida
Family: Astropectinidae
Genus: Astropecten
Species: Astropecten articulatus

Image Links:

https://en.wikipedia.org/wiki/Astropecten_articulatus

http://biochemicalsoul.com/tag/astropecten-articulatus/

Creature 273: Plectaster decanus

Look, don't touch.

Plectaster decanus is a seastar commonly known as the mosaic seastar.

It is renowned for it bright coloration and distinct tile like patterns. But that coloration is there as a warning. These seastars are poisonous. There is a substantial amount of poison in the mosaic seastars skin and it can cause a human's limb to go numb just by holding it.

Distribution:
The mosaic sea star can be found off the coast of temperate Australia at depths of 5 to 200 m

Classification:
Kingdom: Animalia
Phylum: Echinodermata
Class: Asteroidea
Order: Spinulosida
Family: Echinasteridae
Genus: Plectaster
Species: Plectaster decanus

Image Links:

http://www.casc.it/photogallerynew.asp?Page=0&P=1&F=1626&S=2187

http://metazoan.net/8-a-quiet-phylum/

Creature 232: Ptilometra australis

An animal that looks like an alien plant

Ptilometra australis is a species of sea lily which has no common name that I am aware of.

Like many other sea lilies, they superficially look more like plants than animals, wut animals they are.They are filter feeders. Their appendages bear long thin filament which are used for trapping food. They have a stalk which in most sea lily species is long and slender but is reduced in this species. The stalk anchors them to the ocean floor.

Distribution:
Ptilometra australis is found off the coast of Eastern Australia. They are found from fairly near the surtface to depths of over 100m.

Classification:
Sea lilies are echinoderms, the same phylum as sea stars, sea urchins and sea cucumbers. Sea lilies are members of the order Class Crinoidea, a group which used to be much more diverse. Articulata is the only subclass which survives.
Kingdom: Animalia
Phylum: Echinodermata
Class: Crinoidea
Order: Comatulida
Family: Ptilometridae
Genus: Ptilometra
Species: Ptilometra australis

Image Links:

http://en.wikipedia.org/wiki/Ptilometra_australis

http://www.ausmarinverts.net/Echinodermata/Crinoidea/Ptilometra_australis.html

Creature 197: Solaster dawsoni

Star wars.

Description:
Solaster dawsoni is a sea star which is usually referred to as the morning sun star, which is a silly name because the sun is a star.

This sea star is interesting in that it specializes in eating other sea stars. It will even eat other members of its own species. They are so good at eating other sea stars that many sea stars whose distribution overlaps with the morning sun star have evolved defence mechanisms. These range from fleeing the second they make contact to fighting back with pincers or slime. You can watch one of these slow motion battles here:

Distribution:
Solaster dawsoni  is found on continental shelf of the north Pacific ocean.

Classification:
Kingdom: Animalia
Phylum: Echinodermata
Class: Asteroidea
Order: Velatida
Family: Solasteridae
Genus: Solaster
Species: Solaster dawsoni

Image Links:

http://www.jaxshells.org/1074.htm

Video Links:

https://www.youtube.com/watch?v=n9oZcLG51vM

Creature 147: Strongylocentrotus purpuratus

Pretty sea urchin

Description:
Strongylocentrotus purpuratus is known as the purple sea urchin,  probably because it is purple and it is a sea urchin.

Like all sea urchins their body is radially symmetrical but this in echinoderms this is a derived state with bilateral symmetry being primitive. Radially symmetry in this case is not the same thing as radial symmetry in Cnidaria or Ctenophora. Their body plan and things tend to develop in groups of 5 with one medial axis and two lateral axes on each side, think of a star fish here. This is why it has precisely 5 teeth in its ventrally oriented mouth which are used for grazing on kelp. These teeth take 75 days to regrow if they are lost. Contrary to appearances echinoderms have an internal skeleton rather than an external one. Their spines can be moved around by hydraulic pumps and are used for both defense and locomotion.

Strongylocentrotus purpuratus was one of the first species to have its genome sequenced and is considered to be an important point of comparison for human genetics due to the close relationship between the echinodermata and the chordata. They have also traditionally been used a a food source by native Americans.

Distribution:

Strongylocentrotus purpuratus is found off the West coast of North America and is an important member of the kelp forest communities.

Classification:
Kingdom: Animalia
Phylum: Echinodermata
Class: Echinoidea
Order: Echinoida
Family: Strongylocentrotidae
Genus: Strongylocentrotus
Species: Strongylocentrotus purpuratus

Image Links:

http://eol.org/pages/598175/details

http://wiki.hicksvilleschools.org/groups/hsbiology/wiki/55f17/Purple_Sea_Urchin.html

http://war.wikipedia.org/wiki/Strongylocentrotus_purpuratus

Creature 101: Scotoplanes

This is not a balloon animal.

Description:
Scotoplanes is a genus of deep sea cucumbers which are commonly known as sea pigs because apparently they resemble a pig. I think they look more like balloon animals.

They have all the usual adaptions in sea cucumbers such as the self evisceration and the single orifice for eating and excretion.  You can read about these in my post on Johnson's sea cucumbers.

The stubby projections coming out of the base of the animal are used to walk. They are inflated and deflated by hydraulic pumps which are so common in echinoderms. The long protrusions on the top are modified versions of their feet, but their purpose is uncertain. Those tentacle like structures around their mouth are for sifting through the ocean sediment for the bits of food that they eat. They often gather into herds which can contain up to hundreds of individuals and will often face the same direction while herding.

This video explains sea pigs quite well.

Distribution:
Sea pigs are found on the ocean floor in the abyssal zone of the ocean. They are found in the Atlantic,  Indian and Pacific Oceans.

Classification:
Kingdom: Animalia
Phylum: Echinodermata
Class: Holothuroidea
Order: Elasipodida
Family: Elpidiidae
Genus: Scotoplanes

Image Links:

http://www.sanctuarysimon.org/photos/photo_info.php?photoID=3951&search=kw&s=0&page=1

http://cryptidz.wikia.com/wiki/File:Antarctic-sea-pig-de.jpg

Video Links:

https://www.youtube.com/watch?v=_y4DbZivHCY

Creature 59: Coelopleurus exquisitus

This looks more like an alien mother ship than an animal to me.

Description:
Coelopleurus exquisitus is a recently described (2006) species of sea urchin. It's colour and shape are so unusual that they were being sold on E bay before they were known to science.  In fact it was from E bay that the scientific community became aware of the existence of the species. Their skeleton retains the impressive colouration even after they are killed, dried and preserved.

Like most recently described species not a lot is known about them. I still consider them bizarre because of their alien mother ship appearance and the weird method by which they were discovered.

Distribution:
Coelopleurus exquisitus is only known from New Caledonia between depths of 240 and 520m.

Classification:
If you're wondering where this bizarre creature fits in to the tree of life they are in the echinoderm phylum which you may remember from Johnson's sea cucumber. It is a member of the Sea Urchins (class Echinoidea) in an order called Arbacioida defined by their five plated anus.

Kingdom: Animalia
Phylum: Echinodermata
Class: Echinoidea
Order: Arbacioida
Family: Arbaciidae
Genus:Coelopleurus
Species:Coelopleurus exquisitus

Image Links:

http://commons.wikimedia.org/wiki/Category:Coelopleurus_exquisitus#mediaviewer/File:Coelopleurus_exquisitus_(Macro).jpg

http://koghisberg.com/wp-content/uploads/Coelopleurus-exquisitus-38mm-Coppard-Schultz-2006.jpg

Creature 35: Parastichopus johnsoni

A weird looking member of a weird group

A strange looking sea cucumber today. Sea Cucumbers belong to the echinoderm phylum, a diverse phylum which includes starfish, sea urchins, sand dollars and sea lillies. Many members of this phylum will be included later. Echinoderms are in the bilateria radiation of Animals, the group I like to call the 'worm' group. It includes bilaterally symmetrical animals (rough definition). Bilateria normally foolow a two point symmetrical body plan. Echinoderms usually have 5 point symmetry, a fact which is most obvious in starfish but even in sea urchins and sea cucumbers internal arrangements follow a 5 point symmetry body plan. Sea cucumbers may look a bit like bloated slugs but within the bilateria Echinoderms are closely related to our phylum (chordata) than they are to the slug phylum (mollusca). They usually have an internal system of hydaulic pumps which facilitate their movement. Sea cucumbers don't have a brain but instead have a ring of nerves around their mouth which branches out in 5 chords.

Description:

Parastichopus johnsoni or Johnson's sea cucumber is a benthic animal and which has a very limited ability to swim. 

They feed by scooping up ocean floor sediment and filtering out bits of organic waste that have from the pelagic zone. Their mouth is covered with tiny tentacles and cilia for the job.

They earn their place on my blog because of their bright orange coloration with pale white spikes giving it an alien-like appearance. Like other sea cucumbers, Johnson's sea cucumber can eviscerate itself when threatened. If you are wondering "what do you mean eviscerate?" I assure you it is exactly what it sounds like. It spew out its internal organs which stick to the predator. The predator will naturally go for the internal organs and leave the sea cucumber to get away unharmed........ relatively. Yes Sea cucumbers can grow their internal organs back. That's a pretty cool trick.

Distribution:

Sea cucumbers live on the ocean floor from 100m to 650m below sea level in the North East Pacific Ocean.

Classisifcation:

Kingdom: Animalia

Phylum: Echinodermata

Class: Holothuroidea

Order: Aspidochirotida

Family: Stichopodidae

Genus: Parastichopus 

Species: Parastichopus johnsoni