echinodermata

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Odontaster validus

…is a species of seastar that is native to the Southern Ocean and the waters around Antarctica. Like other seastars O.validus is a scavenger and will feed on anything it can find. The only thing that O.validus does not attack is members of its own species, this seems to be due to chemoreceptors. It is thought that this helps them congregate en mass to food sources as well. They are also very sensitive to water changes and as such they have undergone much research to help understanding global warming. 

Phylogeny

Animalia-Echinodermata-Asteroidea-Valvatida-Odontasteridae-Odontaster-O.validus

Image(s): Norbert Wu

Jacksonaster depressum

Jacksonaster depressum (Clypeasteroida - Langanidae) Syn. Laganum depressum, is a species of Sea biscuits inhabiting shallow waters of the Indo-West Pacific region.

The test (exoskeleton) shape of Laganum depressum is oval, with slight pentagonal outline and overall profile flat with slight elevated margin. It exhibits slight concavity on oral side while the aboral side is moderately concave.

The pentaradial symmetry characteristics of Phylum Echinodermata, is highlighted in this species by total five ambulacrum and five interambulacrum. On aboral surface (shown in the photo), each ambularcrum area houses one petal structure while each interbulacrum area appears as inter-petal space. On oral side, the groove between two ambulacral rows forms food groove near the oral opening. 

Living specimens of this sea biscuits generally have light greyish brown color. The petal’s color is prominent dark brown, especially on the outer margin of the petal. The petals cover approximately 80% of radias from aboral centre and have very close interporiferous gap between the distal ends.

References: [1] - [2] - [3] - [4]

Photo credit: ©James Koh [wj]

Locality: Singapore

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6

A BIODIVERSE CORNUCOPIA OF MARINE ANIMALS
Singapore Mega marine Survey 2013
Photographer: Dr Arthur Anker
Date Taken: 2013-06-01

  1. Sea anemone with a miniature sea pen on the disc
  2. Sea pen (Veretillum sp)
    Animalia  >  Phylum: Cnidaria  >  Class: Anthozoa  >
    Subclass: Octocorallia  >  Order: Pennatulacea
  3. Diopatra sp 
    Polychaete worm in the family Onuphidae
  4. Cucumariid sea cucumber
    Animalia  >  Phylum: Echinodermata  >  Subphylum: Echinozoa  >
    Class: Holothuroidea
  5. Gorgonian polyps [sea whips / sea fans]
    Animalia  >  Phylum: Cnidaria  >  Class: Anthozoa  > …
  6. Bornella stellifer -  a nudibranch
    Animalia  >  Phylum: Mollusca  >  Class: Gastropoda
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Horned Sea Star (Protoreaster nodosus)

Also known as the Chocolate Chip or Knobbed Sea Star, the horned sea star is a species of oreasterid sea star that occurs in warm, shallow waters in the Indo-Pacific. Like many other sea stars P. nodosus is an opportunistic carnivore and will feeds mainly on sessile invertebrates and other slow moving invertebrates. The “horns” which give P. nodosus its common name are used mainly to deter potential predators by making it look less palatable.

Classification

Animalia-Echinodermata-Asteroidea-Valvatida-Oreasteridae-Protoreaster-P. nodosus

Images: Kareji and Marta Maria Rubio Texeria

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Basket Star - Astrocladus cf. euryale

Basket stars are a group of ophiuroids (Ophiuroidea - Euryalida - Gorgonocephalidae) in which the five arms are very branched. Most of them remain hidden during the day but come out at night, extending their arms into the water to trap food particles.

The Basket Star Astrocladus euryale (in the photos) is a species native to South Africa, whose arms are branched successively and are covered with pale spots. Sometimes this Basket star is commonly referred to as Gorgon’s Head.

References: [1] - [2]

Photo credit: ©Andrew Taylor | South Africa (2006-2007) | [Top] - [Middle] - [Bottom]

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STARFISH WITH BABIES, BROODING BEHAVIOR  REVEALED

ChrisM/ The equino blog

This motherly starfish is taking care of her starbabies. Some starfish species, such as this one Diplasterias brandti, brood and carry their babies until they are ready to leave the nest, just like some vertebrate species.

SEVERAL different species of sea stars brood. Almost all of them are either cold-water species, living in the deep-sea or at the poles. Sometimes brooding is in temperate water species.. But typically not in the tropics.

Brooding also takes different forms. The oral ‘mouth’ or gastric brooding mode is but one kind. Here is Diplasterias from the Antarctic!  MANY starfish in the Antarctic brood juvenile starfish!

  • Photo: Smithsonian NMNH USARP
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Rosy Feather Star (Antedon bifida)

Taxonomy: Animalia, Echinodermata, Crinoidea, Articulata, Antedonidae, Antedon, A. bifida

Description: A. bifida has ten divided arms, reaching 10cm in maximum length. These arms range in colour (such as red, white, pink, and yellow), and can have a blotched or marbled appearance. As with all feather stars, these arms are covered in pinnules. The ventral side of the feather star has tube feet in groups of three, as well as 20 cirri, which are used to grip to surfaces.

Lifestyle: A. bifida is a suspension feeding echinoderm, consuming small planktonic organisms with its pinnules. Food is then transported along the ambulacral groove towards the mouth. Whilst they are primarily stationary, this species can walk on its tube feet and cirri, as well as ‘swim’ by undulating its arms. This species undergoes brooding behaviour, covering embryos in her arms once they have been externally fertilised. A. bifida is found up to depths of 200m along the northwestern coasts of Europe, as well as in West Africa and other Europea regions.

Photos by Sacha Lobenstein, Habitats, and Mergullo.

2

Field trip to Bodega Bay (1/26/14) Finale: My favorite pictures from the day

1) Bat Star and Pisaster right next to each other, with Pisaster’s tube feet visible. Pisaster was more prevalent where there more waves, since it mostly ate mussels, while the bat stars ate more algae, which grew with less waves, so it was cool to see them both right next to each other

2) Scyphozoan Jelly on the mudflats. The red spots are eyespots. We thought the fluffy tan things in the middle might be the oral arms retracted in for low tide. We also thought it (and all the others we found) were dead, but then we put them in a bucket and they were fine. (One thing I learned on this field trip was that cnidarians can in fact survive on the coast at low tides.)

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Sea Potato

(Echinocardium cordatum)

is a species of heart urchin found in shallow tidal regions around the world. The name sea potato probably comes from the animals brown coloration and short spines making it look sort of similar to a potato(they look more like garlic to me). They spend most of their lives in burrows dug 10-15 cm under the sand, these burrows have channels for respiration  and sanitation as well. the urchin waits and collects any edible material that rests on top of the burrow. Other animals like amphipods and bivalves are known to share burrows with the sea potato as well.

Phylogeny

Animalia-Echinodermata-Eleutherozoa-Echinoidea-Spatangoida-Loveniidae-Echinocardium-cordatum

Source,Source

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Peronella lesueuri a beautiful sand dollar of importance in coastal ecosystem processes

The striking Peronella lesueuri (Clypeasteroida - Laganidae), is a large sand dollar up to 15 cm in diameter, with a wide Indo-Pacific distribution. The most noticeable and amazing feature of this species is its bright pink when alive, hence its common name of Pink sand dollar.

It is a shallow burrower and occurs at densities which may influence surface sediment chemistry and community dynamics. Therefore, knowledge of seasonal and diet movement rates and rhythms of this species are a key of interest in understanding coastal sediments biogeochemical dynamics.

References: [1]

Photo credit: ©Loh Kok Sheng | Locality: Pulau Sekudu (Frog Island), off Chek Jawa, Pulau Ubin, Singapore (2009) | [Top] - [Bottom]

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2

Sea Apple - Pseudocolochirus violaceus

It may not seem much an apple, nor a cucumber, but these are colorful sea cucumbers commonly known as Sea Apples belonging to the species Pseudocolochirus violaceus (Holothuroidea - Dendrochirotida - Cucumariidae), which occurs in the Indian Ocean and the western part of the Pacific Ocean.

Sea apples are about 18 cm long. They usually are purple, but also can be blue, red, white, and yellow. Three rows of tube feet run along the bottom side of the animal. The top side has two rows of tube feet as well as small scattered tube feet. The body is curved so that the mouth and anus point upward. They have ten tentacles which are bushy purple to red and have white tips. The pieces of the body wall skeleton are rounded, smooth plates with a few holes.

When relaxed, the normal shape is short and sausage-like as with most other sea cucumbers. When stressed, however, it may inflate itself into a large round ball. 

Sea apples live partly hidden to fully exposed with tentacles expanded, even during the day. They feed continuously, capturing large food particles with outstretched branching tentacles that are lightly coated in mucus. 

These beautiful sea cucumbers unfortunately are harvested for the aquarium trade. Ironically, they do not make good aquarium specimens as they are often toxic to their tank mates. 

References: [1] - [2] - [3]

Photo credit: [Top: ©René Cazalens | Locality: Komodo, Indonesia, 2010] - [Bottom: ©Chuck and Jean | Locality: Manila Ocean Park, Philippines, 2008]

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