Invertebrates

1. Invertebrates

5. Phylum Porifera - Sponges • they have an asymmetrical body • they have specialized cells that are not organized into tissues or organs, • the cells act independently • as the name implies sponges have a number of pores, these pores allow water to flow through the animal where food particles are filtered out by special cells • nutrients are then passed from cell to cell within the sponge • sponges have a skeleton but it is not one that is organized in a set pattern • the skeleton can either be composed of hard spicules which also aids in protecting the sponge or it can be soft and flexible from spongin fibers • sponges are considered sessile, found attached to the ocean floor as adults • sponges reproduce both asexually from fragmentation or budding or sexually • sponges are hermaphroditic meaning they can produce both sperm and eggs but not at the same time

7. Phylum Cnidaria – Jellyfish, Corals, Anemones, & Hydroids • they have radial symmetry • there are two body forms, medusa - free floating form & polyp – attached to ocean floor • cells are arranged into tissue layers that carry out specific functions • they have tentacles with specialized stinging cells surrounding a mouth • the mouth leads into a gastrovascular cavity, therefore digestion begins outside • of the cell meaning they can take in food that is larger than their cell size • they reproduce both asexually and sexually usually alternating the stage of reproduction

8. Phylum Platyhelminthes – Flatworms – planaria, tapeworms, flukes • flatworms have a simple body plan • they have tissues that are organized into organs • they are bilaterally symmetric • since they do not have a thick body cells are close to the surface and therefore oxygen • and carbon dioxide can pass easily through the cell layers • they have a gastrovascular system which is close to all of the animal’s tissues in order to pass nutrients from it. • they are hermaphrodites, sperm from another individual will be used to fertilize the eggs • Phylum Nematoda – Roundworms • they have bilateral symmetry with tissues organized into organs • they have a digestive system • some species in this phylum are parasitic

9. Phylum Mollusca – Snails, Slugs, Clams, Squid, Octopus • they have a true body cavity, where the internal organs are found within an • enclosed area of the body • they have internal organs which have specific functions (digestion, circulation, respiration) • they have bilateral symmetry • they have a body plan that is divided into three parts: the mantle region, • the visceral mass and the foot • most have an external skeleton protecting the soft body parts, some have an smaller internal skeleton and some have no skeleton at all • they reproduce sexually • three of the major classes of molluscs include bivalves, gastropods, and cephalopods • they have gills for respiration • they have an open circulatory system though squid and octopi have closed ones

10. Phylum Annelida – Segmented Worms - earthworms they have bilateral symmetry, with tissues that form organ systems they have sensory organs and can respond to light, touch, and moisture they have a primitive brain they have a digestive system, with areas of the gut that perform different functions they have a closed circulatory system they are hermaphrodites, but mating occurs between two individuals they have a hydrostatic skeleton, meaning fluid trapped in the body cavity or coelom gives the animal support for muscle contraction to take place

11. Phylum Echinodermata – Spiny Skin Animals - sea stars, sea urchins, sea lily they have radial symmetry with tissues that form organs with specific functions they have an endoskeleton, in some species it is flexible and in others it is rigid they have a water vascular system which is a series of canals that allows fluid to move through it creating pressure differences that allow the them to grab items, move, and it also aids in gas exchange they have no gills, nor lungs they have no heart, fluid is brought into the coelomic cavity and nutrients pass through cells they reproduce sexually with separate sexes, but are capable of regeneration