Assignment+Two

1/31/11

Observe the chart located below. Pick one organism from each of the four zones indicated in the chart and describe it's ability to live in the zone when taking into account the substrate, means of reproduction, feeding method, exposure to the air, defense mechanism, and the rise and lowering of the tide.

Sea Star - some Sea stars have the ability to extrude their stomachs, off the substrate and secrete mucus strands from the grooves between the rows of tube feet. Sea stars usually reproduce by free-spawning: releasing their gametes into the water where they are fertilized by gametes from the opposite sex, they also gather into groups when they are ready to release there egg, this is to increase the chance of reproduction. Most eat clam, oysters and snail and some are detritivores meaning they eat decomposed animals. Because of the water vascular system, sea stars and other echinoderms dont have the ability to filter pollutants and toxins out of the water they inhabit.Sea stars use a self-amputation mechanism. They detach their own limb to escape a predator. Their limbs grow back very quick.

Hermit Crab -Hermit crabs live in different depths of saltwater, from shallow reefs and shorelines to deep sea bottoms. A female hermit crab will lay eggs in the ocean and the male will fertilize them, with the first two the nauplus and protozoea happening in the egg. Most hermit crab larvae hatch at the third stage, which is the Zoea. This is a larval stage where the crab has many long spines, a narrow abdomen, and a big fringed antennae. After several zoeal moults, the last stage come up which is the megalopa stage. Hermit crabs eat They eat vegetables, fruit, as well as fish and meat. They are very picky about the things they eat. The more the crab is exposed to low humidity the more it suffers, the air they breathe has to be humid or else there gills dry out. Hermit crabs can easily freeze to death, water that hasn't been declorinated will also kill them.

Periwinkle - Living in a Splash zone, Periwinkles Once a year they expend extra energy in reproduction. These snails are separate sexed - the male needing to find a female for mating. In this species, the males appear unable to distinguish the opposite sex until actually trying to mate. In spring and summer males become very active.When they are hungry they emerge, first eating the hardened mucus and then they crawl about leaving slime trails, like land snails. They glide along; scraping the plant scum off the rocky surface with a special structure in their mouth called a radula. It could tolerate limited air exposure and its defense mechanism can be its unusua; yellow color.

Rock Louse  - Live permanently in cool, moist habitats, alternates between dry and wet condions so it can replace water previously lost by evaporation. They usually prefer to eat brown algae and detritus, The life span of these isopods is about 1.5-2 years with the breeding period in the spring and early summer months. At night and at low tides in cool weather, forages throughout the intertidal zone. It's a scavenger, plus feeds on microscopic algae. They must keep their gills moist but will drown if submerged in water. Baombolia, N 10:56 pm