Cnidarians

Characteristics Cnidarian means Thistle Referring to the stinging cells (nematocysts) that all members possess All aquatic Radial symmetry Body has a single opening through which food and wastes pass Has a gastrovascular cavity where digestion begins

Symmetry

Gastrovascular cavity

Nematocysts

Some can move around, others are sessile Two tissue layers, the ectoderm(outer) and the endoderm ( inside) Simple nervous system and muscle tissue Reproduce asexually by budding and sexually by producing gametes. Cnidarians are hermaphrodites

Hydra, Jellyfish, Sea anemones, Coral

Platyhelminthes Means flat and wide Simplest animals with bilateral symmetry Have organs and organ systems Have an anterior end and so move in a forward direction 3 tissue layers: endoderm, mesoderm and ectoderm Lack a body cavity Some have a primitive brain and sensory organs Planarians are free-living, while tape worms and flukes are parasites Reproduce sexually and asexually

Planaria, tape worms and flukes

Nematode Worms Means thread-like Commonly called roundworm Some are free-living and some parasitic Distinct head and organ systems Tube within a tube body plan Has a pseudo coelom (body cavity) Sexual reproduction Some species are hermaphrodites

Annelids

Annelida means ring Referring to the body being segmented into repeating units The only group of segmented worms They live on land and in water They have complete digestion, a closed circulatory system, a ventral nerve cord, a nephridial excretory system, and a true body cavity Digestion is extracellular ( in special compartment in the body, not in cells) Sexual reproduction, internal fertilization, some are hermaphrodites

True body cavity

Earthworms, clamworms, leeches

Gross!!!!

In 1994, a woman's scalp was ripped off when her hair was yanked into moving machinery. Doctors performing micro-surgery at the University of Southern California reattached the scalp, but one area swelled with congested blood. They applied leeches, one at a time for eight days, to suck up stagnant blood. Eventually new capillaries, or tiny blood vessels, formed in the scalp wound, leading to healing circulation.

Mollusca Means soft-bodied unsegmented Most live in water, a few (slugs) live on land Most have an internal or external shell Have a mantle (fold in the body wall that lines the shell) Muscular foot and/or tentacles All except bivlaves have a radula and a well-developed head Most have an open circulatory system, some have closed circulation Many respire using gills, slugs use a hole in the side of their head and breath through their skin Gums to bums digestion

Arthropods The most successful phylum (10 6 to 10 7 species) Means “jointed foot” but have jointed appendages Very diverse group Reproduce sexually, most have separate sexes Rigid, jointed exoskeleton provides a waterproof protective armor, a site for muscle attachment, protection from drying Well developed nervous system Most have an open circulatory system, breath using gills, trachea, book lungs Well developed excretory system ( kidneys) One way digestive system

Echinoderms Means spiny skinned Most advanced group of invertebrates Radial symmetry Digestion is extracellular, one way digestive system Reproduction is sexual, asexual powers of regeneration Does not have a centralized nervous system Has an endoskeleton made of calcium carbonate plates Water -vascular system with “tube feet”helps catch food, with movement and gas exchange