Invertebrate- animal that does not have a backbone Vertebrate- animal that has a backbone Radial Symmetry- all parts of an animal’s body are organized in a circle around a central axis Bilateral Symmetry- body parts are organized into two equal halves which mirror each other Protostome- an organism whose embryonic tissue develops into the mouth first and anus second. Cephalization- Concentration of sensory organs in an anterior head. Deuterostome- an organism whose embryonic tissue develops into the anus first and mouth second.

Phylum Porifera (1) Example: Sponges Sponges are the simplest of animals that carry out all processes by the movement of water through pores Characteristics: Lack definite symmetry No germ layers or mouth. Reproduce both sexually and asexually All process carried out a few specialized cells Internal Fertilization – Sperm travels to another sponge, fertilizing another sponge internally. Immobile (sessile)

Phylum Platyhelminthes (2) Example: Flatworms Characteristics: Bilateral symmetry Protostome Digestive system is branched with a single opening (mouth) with a specialized pharynx that pumps food into the digestive system Cephalization – in some the head encloses ganglia – a group of nerve cells Some are parasitic (ex: Flukes and tapeworms) A flatworm has a very simple nervous system with two nerve cords running down either side. It has two simple brains called ganglia, which are simple bundles of nerves.

Acoelomates: an invertebrate lacking a coelom; especially the group comprising the flatworms, having bilateral symmetry and one internal digestive cavity.

Phylum Nematoda (3) Examples: Roundworms Characteristics: Body cavity, pseudocoelom, located between endoderm and mesoderm Three Germ layers. Have complete, one-way digestive tracts (mouth and anus) Protostome Bilateral symmetry Nematoda contains the most members, most are microscopic, many parasitic These parasites can affect nearly any plant or animal. The three types of parasitic roundworms are: Hookworms, Pinworms, and Guinea worms.

Phylum Arthropoda (4) Examples (most species) : insects, crabs, centipedes, spiders Characteristics: Arthropods have a segmented body, tough exoskeleton (on outside), and jointed appendages. Most successful of all invertebrates Many specialized organs Three Germ Layers with coelom Bilateral symmetry

Phylum Echinodermata (5) Examples: sea stars, sea urchins, sea cucumbers, and sand dollars. Characteristics: Most have spiny skin, an internal (endo) skeleton, a water vascular system, and suction-cuplike tube feet. Adults have radial symmetry (can be split in two halves). Adults possess five-part body plan Deuterstome Three germ layers with a coelom

Phylum Chordata (6) Chordates all had/have a notochord, a hollow nerve cord, pharyngeal slits, and a tail at some stage of development. Examples (All vertebrates and some invertebrates): Mammals, Reptiles, Birds, Amphibians Characteristics (at some stage of development): Notochord – back skeletal support Hollow nerve cord – nervous system integration Pharyngeal slits – Water passage Tail – Has segments used for movement Therm ~ Endo regulate their own body temperature whereas Ecto cannot.

Phylum Mollusca (7) Examples: snails, slugs, clams, squids, octopi Characteristics: Soft-bodied that usually have a shell 4 part body plan Foot – movement Mantle – layer of tissue covering body Shell – created my mantle, lost in some members Visceral mass – internal organs Three germ layers with coelom Bilateral symmetry. Open Circulatory System: The hemocoel is the space between cells within tissues. Blood is pumped through the hemocoel and cells receive oxygen by diffusion (No blood vessels).

Phylum Annelida (8) Examples: earthworm, leeches, polychaetes, and feather dusters Characteristics: Worms with segmented bodies. Three germ layers and a true coelom (muscle-covered space) Bilateral symmetry Cephalization Protostome Closed Circulatory system – Blood flows in a circuit through actual vessels.

Aquatic Annelid Adaptations

Phylum Cnidarians (9) Examples: Jellyfish, Hydra, Sea Anemones and Corals Characteristics: Two layers – an endoderm and ectoderm, with a layer of jelly-like material between. A single mouth/anus surrounded by stinging tentacles A nerve net to detect stimuli Hydrostatic skeleton allow the animal to move External fertilization – fertilization of sperm and egg takes place outside of the organism.

Hydrostatic Skeleton: is a structure found in many soft-bodied animals consisting of a fluid-filled cavity, the coelom, surrounded by muscles.