There are three different types of slate pencil urchin
- Eucidaris tribuloides found in the Atlantic Ocean, close to the shore,
- Heterocentrotus mammillatus found in the tropical waters of the Indo-Pacific region, but mainly Hawaii,
- Heterocentrotus trigonarius also found in the tropical waters of the Indo-Pacific region.
.jpg/798px-Eucidaris_tribuloides_(Slate-pencil_Urchin).jpg) |
| Eucidaris tribuloides Photo: Nick Hobgood (Wikimedia Commons) |
 |
| Heterocentrotus trigonarius Photo: David Burdick (NOAA) |
 |
| Heterocentrotus mammillatus Photo: Dr. Dwayne Meadows, NOAA/NMFS/OPR |
Eucidaris tribuloides
These pencil urchins are brown to reddy brown. They range from about 2-5 inches in size. Their long spines are arranged in 10 rows with smalled spines between. Broken spines can be replaced. The colour of their spines depends upon which algae covers them.Their habitat is a shallow coastal one up to depth about 50 m. They are often found in seagrass beds, under rocks or in coral crevices. Their main diet is algae.
Heterocentrotus mammillatus
These slate pencil urchins are bright red. They have three types of spines. The longest are triangular which keep predators at bay. Underneath, they have shorter, flatter spines to clamp onto the reef. Finally, the whole body is encased in flat, armour-like spines.Heterocentrotus trigonarius
These have longer spines than Heterocentrotus mammillatus, although I can't find any precise details on either species which would enable this to be used to distinguish them.Carbon Dioxide Levels in the Sea
In tests on various sea creatures, some built more shells when dissolved carbon dioxide levels, and thus acidity, were raised. When the level was raised to seven times the current level, the following was observed.This led to the dissolving of aragonite—the form of calcium carbonate produced by corals and some other marine calcifiers. Under such exposure, hard and soft clams, conchs, periwinkles, whelks and tropical urchins began to lose their shells. “If this dissolution process continued for sufficient time, then these organisms could lose their shell completely,” Ries said, “rendering them defenseless to predators.” [WHOI: News Release : In CO2-rich Environment, Some Ocean Dwellers Increase Shell Production]The pencil urchins used in these experiments were Eucidaris tribuloides.
Summary of Sources
Pharyngula: Mary's Monday MetazoanTropical Fish Magazine: Eucidaris Tribuloides
WoRMS taxon details: Eucidaris tribuloides
WoRMS taxon details: Heterocentrotus mamillatus
WoRMS taxon details: Heterocentrotus trigonarius
Hawaiin Isles Hump Back Whale: Heterocentrotus mammillatus
WHOI: News Release : In CO2-rich Environment, Some Ocean Dwellers Increase Shell Production
Wikipedia: Eucidaris tribuloides
Wikipedia: Heterocentrotus mammillatus
Wikipedia: Heterocentrotus trigonarius
Species-identification.org: Eucidaris tribuloides
Wikipedia: Aragonite
.jpg){kind=link}
No comments:
Post a Comment