Invertebrates Notes A. Porifera (sponges): Porifera literally means. Most sponges are. They are that collect food particles from the water as they pass through flagellated cells called. These cells then pass food to that are able to move about the sponge and distribute nutrients to the entire organism. Recall sponges do not have specialized tissues and are therefore. B. Cnidaria (jellies, hydra, sea anemones, and corals): They have 2 body forms: the floating and sessile. The basic body plan is a sac with a central digestive compartment called the. There is a opening for both the mouth/ anus. Cnidarians have no, and only a. They also have a skeleton composed of fluid held under in a closed body compartment. C. Platyhelminthes (flatworms-like planarians, tapeworms, and flukes): These acoelomates can be free-living (planarians), internal animal that suck blood/tissues (flukes), or internal parasites in the tract (tapeworms). Recall that flatworms like planarians have to maintain osmotic balance. They have a digestive tract with a single opening. Located at the anterior end of flatworms, are ganglia or clusters of cells.
D. Rotifera (rotifers): They inhabit fresh water primarily and have a digestive tract. Some species consist of only and produce more females from unfertilized eggs. This is called. They are feeders that use cilia on their head to pull in food. E. Nematoda (roundworms like nematodes): Recall one species of nematodes is widely used as a model organism. Many are found in moist or moist plant and animal tissues. One species causes trichinosis that humans acquire from undercooked containing juvenile worms. They have a digestive tract and are pseudocoelomates. F. Mollusca (snails, slugs, chitons, bivalves [clams], octopuses, and squids): Most mollusks have. Squids have an reduced shell, but octopuses have no shell. All mollusks have a simple body plan of 3 parts: a muscular used for movement, a containing internal organs, and a which is a fold of tissue over the visceral mass.
The bivalves include clams, and. The gastropods include and. The cephalopods include and. Octopuses have a highly developed nervous system and a large brain. G. Annelida (segmented worms like earthworms and leeches): Annelida literally means. Recall segmented worms like earthworms have circulatory systems and (excretory tubes with ciliated funnels) to excrete wastes from their bodies. They have a brain-like pair of near their anterior end. H. Arthropoda (spiders, insects, crustaceans): They have appendages, a developed nervous system, and exoskeletons of. Some are born as that change shape slowly as they grow into adults and others are born as (maggots) that undergo metamorphosis. Recall arthropods have an circulatory system and that for excreting wastes, arthropods such as insects use tubules. These outpockets of the digestive system remove metabolic waste from the. Also recall breathing takes places through or pores on the body surface.
I. Echinodermata (sea stars, sea urchins, brittle stars, sea cucumber, sand dollars): These animals are symmetrical as adults and often have spokes. Unique to echinoderms is the water system-network of hydraulic canals branching into extensions called that function in locomotion, feeding, and gas exchange. J. Chordata (2 invertebrate subphyla and ALL vertebrates): Chordates have 4 main features: a (flexible rod on dorsal side later becomes the backbone in many animals), a dorsal (later becomes the brain and spinal cord), (some disappear during embryonic development, some keep for gas exchange), and a muscular (in many the tail is lost during embryonic development). The 2 main groups of chordates are the invertebrate chordates like and and the vertebrate chordates like fish, amphibians, reptiles, birds, and mammals.