Echinoderms

Echinoderms are the "spiny skinned" animals of the ocean. There are around 600 species of echinoderms, and these include species of Sea stars, sea urchins, and sea cucumbers. Unlike other invertebrates, Echinoderms are specific to the ocean and cannot be found in any other environment. All echinoderms have radial symmetry which means that all their body parts come the center of the organism; most have 5 part symmetry. Tube feet powered by a water vascular system is also a common trait of echinoderms. Echinoderms are also benthic organisms although many are planktonic during their larvae stage. (1)

Species 1:

Purple Sea Urchin - Strongylocentrotus purpuratus (2)

Habitat: Where the kelp is attached to the ocean floor by their holdfast(3)

Niche:(2) They control the amount of algae in the ocean and their habitat. This can be a problem in Kelp forests because, if they are not controlled, sea urchins can eat a whole kelp forest in a very short time.

Adaptation:(2) Purple sea urchins have large spines to protect them from predators and other threats. Their mouth is also located on the bottom of their body so that they can eat algae and kelp as they move along the ocean floor.

Life Cycle:

External fertilization(2)
Males and females release gametes into the ocean(2,3)
Fertilized eggs attach to substrate to develop into an urchin(3)
Breed yearly usually around the beginning of the year
- Start breeding at around 2 years old(2)

Sources:

1. Bird, Jonathan. "The Wonders of the Seas: Echinoderms." The Wonders of the Seas: Echinoderms. Accessed January 26, 2017. http://www.oceanicresearch.org/education/wonders/echinoderm.html.

2. Vickery, Katelyn, and Maria Fam. "Portfolio." The Purple Sea Urchin. Accessed January 26, 2017. http://tolweb.org/treehouses/?treehouse_id=4879.

3. Worley, Alisa. "Strongylocentrotus Purpuratus." Animal Diversity Web. Accessed January 26, 2017. http://animaldiversity.org/accounts/Strongylocentrotus_purpuratus/#habitat.

Species 2:

Common Brittle Star (Ophiothrix fragilis)

Habitat: Found in the North Sea, most commonly found on tide-swept rock and coarse sediment (2)

Niche: Brittle stars are omnivores and filter feeders (4)

Adaptation: Brittle stars live in concealed places in the kelp forest and are able to camouflage and blend in with its surroundings to reduce predation. (4)

(3)

Life Cycle: (1)

The brittle star develops from a free ranging larva which feeds on algae
Brittle stars are ready for breeding at two years old once they sexually mature
Become fully grown in three to four years
Usually live up to five years

Sources:

1.) "Brittle Star." Brittle Star. Accessed January 27, 2017. http://wiki.hicksvilleschools.org/groups/hsbiology/wiki/54818/Brittle_Star.html.

2.) "Brittle Stars: Secrets of the Ophiuroidea." Reef To Rainforest Media, LLC | CORAL Magazine | AMAZONAS Magazine | Microcosm Publishing. Accessed January 27, 2017. http://www.reef2rainforest.com/2013/08/28/brittle-stars-secrets-of-the-ophiuroidea/.

3.) "Common Brittle Star – Ophiothrix Fragilis - Other." It's Nature - News, Videos & Pictures From the Natural World. Accessed January 27, 2017. http://www.itsnature.org/sea/other/common-brittle-star/.

4.) The Editors of Encyclopædia Britannica. "Brittle Star." Encyclopædia Britannica. October 23, 2008. Accessed January 27, 2017. https://www.britannica.com/animal/brittle-star.

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