Mature echinoderms have five spots facing outward from the center of the body with a mouth below and the anus on top. There are exceptions to this plan, however; some echinoderms lack an anus and others, such as crinoids, have their mouth and anus on the same side of the body. Scientists refer to the side of the body with the mouth as the oral side and the side with the anus as the aboral side. Crinoids, ophiuroids, and holothuroids have tube feet to help scoop up food particles that float toward their body. Other types of echinoderms such as asteroids are carnivorous and will surround or dump their stomach onto their prey. Some echinoids hong kong email list even have teeth used to chew and disassemble plants and small animals.
Most echinoderms reproduce sexually by producing larvae that feed on phytoplankton until they reach maturity. Some species of echinoderms develop their offspring in embryo sacs located on the outside of their bodies.
Sea urchin, Lembei Strait, Suluwesi, Indonesia 2005Echinoderms have fascinating aquatic vascular systems that likely originated from some sort of respiratory system that evolved to include food gathering and movement. They perform these tasks through the use of their numerous hollow tube feet that resemble tentacles. There are two rows of tube feet on the outside of the body that fill with seawater so that when the animal expands or contracts, water is drawn into the feet. Once filled, the feet extend outward allowing the animal to walk. The suckers located at the tips of the tube feet are often used to grab prey or to hold onto solid objects when the echinoderm wants to remain attached to something.
Feather star, Lembei Strait, Suluwesi, Indonesia 2006The most familiar echinoderm known to humans is probably the starfish, categorized in the superclasses Asterozoa and Cryptosyringida. There are two classes of starfish including Asteroidea and Ophiuroidea. True starfish and sun stars are in the Class Asteroidea, while brittle stars and basket stars are in the Class Ophiuroidea.At first, this canyon, known as Water Canyon, might look like any ordinary Bryce Canyon. It's not. From 1890 to 1892, Mormon pioneers worked with picks and shovels to carve an irrigation ditch from the East Fork of the Sevier River, across the Paunsaugunt Plateau, into this canyon.
