Gastropods Lauren Cheevers

Life Cycle Snail Life Cycle Slug Life Cycle Three main stages make up their life cycle: the egg stage, the immature stage and the adult stage. Slugs are hermaphroditic, meaning that they possess both male organs and female organs. They can take between 10 and 100 days to hatch depending on season, with warmer weather hatching eggs sooner. The immature stage lasts for less than a year before the adult stage is reached and mating can begin. year of age when capable of mating. There is a ritual courtship that occurs before mating. Terrestrial snails are hermaphroditic, which means that they are capable of producing both eggs and semen. Two snails fertilize one another; both will lay fertilized eggs. The eggs begin to develop immediately and hatch after a period of four weeks. Their outer shell is already forming. At this stage, snails are colorless and nearly transparent. As they begin to feed regularly, their colors appear, and they already look like miniature versions of their adult stage.

Circulatory System Gastropods have open circulatory system and the transport fluid is hemolymph. Hemocyanin is present in the hemolymph as the respiratory pigment. Mollusk have a heart, blood and blood vessels

Excretory System The primary organs of excretion in gastropods are nephridia (get rid of wastes) which produce either ammonia or uric acid as a waste product. The nephridium also plays an important role in maintaining water balance in freshwater and terrestrial species. Additional organs of excretion, in some species, include pericardial glands in the body cavity, and digestive glands opening into the stomach.

Nervous System A Mollusk has no formal nervous system, but has a series of ganglia that conduct impulses. The upper pair of tentacles on the head have eye spots. Like most animals they have eyes however they have no hearing. Eyes in gastropods range from simple ocelli which cannot process an image being only able to distinguish light and dark, to more complex pit eyes, and even to lens eyes.

Symbiotic Relationships None Found 

Crustaceans Lauren Cheevers

What are they ??? Crabs Shrimp Lobsters A crustacean is an arthropod that has a hard, exoskeleton, two pairs of antennae, and a mouth for crunching and grinding. Crabs Shrimp Lobsters

About Crustaceans Crustaceans belong to the Phylum Arthropoda (jointed feet). All Arthropods have jointed appendages. All Arthropods have an exoskeleton.

Reproduction They reproduce sexually Fertilize externally The majority of crustaceans have separate sexes. A small number are hermaphrodites, such as barnacles. Some may even change sex during the course of their life. Studies have found some eggs that are produced by a female without needing fertilization by a male. This occurs in many branchiopods and certain "higher" crustaceans, such as the Marmorkrebs crayfish. Most mate seasonally and return to the sea to release the eggs. Others, such as woodlice, lay their eggs on land, in damp conditions. In most decapods, the females retain the eggs until they hatch into free-swimming larvae.

Life Cycle In many groups of crustaceans, the fertilized eggs are simply released into the water column, while others have developed a number of mechanisms for holding on to the eggs until they are ready to hatch. Some attach them in rows to rocks and other objects, carry the eggs between their thoracic limbs, or in special thin-walled sacs, while others have them attached together in long, tangled strings. Juvenile and adult stages

Respiratory System Gills are special respiratory organs that help some Aquatic members- gills for gas exchange; terrestrial members- tracheal system of branched tubes leading from surface throughout body. Many of them have gills that help them take in oxygen and give off carbon dioxide. Gills are special respiratory organs that help some animals breathe and get oxygen from the water.

Circulatory System   Open circulatory systems in which a heart pumps blood through the body.

Digestive System They filter feed, scavenge, or are predatory Use appendages for food getting and movement a pair of digestive glands that absorb food

Excretory system Food passes through the gut is broken down and removed through the anus

Symmetry/Body Plan Bilateral symmetry Two main body segments- Cephalothorax Abdomen Molting is when the exoskeleton is shed as the organism outgrows it.

Nervous System The crustacean nervous system consists basically of a brain connected to a ventral nerve cord of ganglia, or nerve centers. Antennae Eyes

Symbiotic Relationships A few taxonomic units are parasitic and live attached to their hosts (including sea lice, fish lice, whale lice, tongue worms all of which may be referred to as "crustacean lice")

Other important characteristics Crustaceans can re-grow certain parts of their body. Found throughout the oceans of the world some adapted to land Are an important food source for other marine organisms Their tough outer skeletons contain lime

Questions???