Phylum: Porifera The Sponges Fig. 12.CO

Phylum Porifera, which means “pore bearer.” Porifera (sponges) Summary: Phylum Porifera, which means “pore bearer.” Sponges are asymmetrical aquatic animals that have a variety of colors, shapes, and sizes. Many are bright shades of red, orange, yellow, and green. Filter Feeders Can reproduce sexually and asexually (gemmules).

Sponge Structures: -Choanocyte (collar cells): flagellated collar cells which keep the current flowing by beating flagella. They trap and phagocytize food particles passing by. They also can produce sperm -Archaeocytes: Cells which digest particles to provide nutrients. -Amoebocytes: amoeba-like cells found throughout the sponge; store, digest and transport food, excrete wastes, secrete skeleton and also may give rise to buds in asexual reproduction. -Epithelial-like cells: These cells are thin and flat. They contract in response to touch or to irritating chemicals. In so doing, they close pores in the sponge. -Pore Cell: Surrounding each pore is a pore cell. Pore cells allow water carrying food and oxygen into the sponge’s body.

Section 26.1 Summary – pages 693-697 Osculum A Sponge Pore cell Epithelial-like cells Amoebocyte Collar cells Direction of water flow through pores Spicules Section 26.1 Summary – pages 693-697

Mr. Walker Invertebrate Zoology Cnidarians Mr. Walker Invertebrate Zoology

Section 26.2 Summary – pages 698-705 What is a cnidarian? Cnidarians (ni DARE ee uns) are a group of invertebrates made up of more than 9000 species of jellyfishes, corals, sea anemones, and hydras. They can be found worldwide, and all but a few cnidarians live in marine biomes. Section 26.2 Summary – pages 698-705

Section 26.2 Summary – pages 698-705 Body structure Because a cnidarian’s body is only two layers of cells, no cell is ever far from water. Mouth A cnidarian’s body is radially symmetrical. It has one body opening and is made up of two layers of cells. Tentacle Cavity Inner cell layer Jellylike layer Bud Carbon dioxide and other wastes can move out of a cnidarian’s body cells directly into the surrounding water. Disc Outer cell layer Section 26.2 Summary – pages 698-705

Section 26.2 Summary – pages 698-705 A Cnidarian Cnidarians display a remarkable variety of colors, shapes and sizes. Some can be as small as the tip of a pencil. Most cnidarians have two distinct body forms during their life cycles. - A polyp is the sessile form of a cnidarian. Its mouth is surrounded by tentacles. Examples of polyps include sea anemones, corals, and hydras. Section 26.2 Summary – pages 698-705

Section 26.2 Summary – pages 698-705 A Cnidarian Tentacles A medusa is the free- swimming form of a cnidarian. It possesses an umbrella-shaped, floating body, called a bell, with the mouth on its underside. Section 26.2 Summary – pages 698-705

Section 26.2 Summary – pages 698-705 Reproduction in cnidarians Medusae Male Female Asexual reproduction Egg Sperm Sexual reproduction Larva Polyp Section 26.2 Summary – pages 698-705

Section 26.2 Summary – pages 698-705 Digestion in cnidarians Cnidarians are predators that capture or poison their prey using nematocysts. A nematocyst (nih MA tuh sihst) is a capsule that contains a coiled, threadlike tube. The tube may be sticky or barbed, and it may contain toxic substances. Nematocysts are located in stinging cells that are on tentacles. Section 26.2 Summary – pages 698-705

Section 26.2 Summary – pages 698-705 Digestion in cnidarians Once captured by nematocysts, prey is brought to the mouth by contraction of the tentacles. Mouth Gastrovascular cavity Polyp Mouth Medusa Section 26.2 Summary – pages 698-705

Section 26.2 Summary – pages 698-705 Hydra eating daphnia Digestion in cnidarians The inner cell layer of cnidarians surrounds a space called a gastrovascular (gas troh VAS kyuh lur) cavity. Cells adapted for digestion line the gastrovascular cavity and release enzymes over captured prey. Any undigested materials are ejected back out through the mouth. Section 26.2 Summary – pages 698-705

Section 26.2 Summary – pages 698-705 Nervous system in cnidarians A cnidarian has a simple nervous system without a control center, such as a brain like that of other animals. In cnidarians, the nervous system consists of a nerve net that conducts impulses to and from all parts of the body. The impulses from the nerve net cause contractions of musclelike cells in the two cell layers. Section 26.2 Summary – pages 698-705

CTENOPHORA

Common Names Ctenophores are often called “comb jellies,” “sea gooseberries,” “sea walnuts,” or “Venus’s girdles.” There are about one hundred species of Ctenophora that have been discovered. Ctenophores have two digestive openings, but rarely use the anus for defecation Digestive system consists of mouth, pharynx, and stomach with a canal system Have no CNS or brain, but a nerve net All Ctenophores have a distinct larval form before adulthood

Characteristics All organisms in Ctenophora have comb rows that are actually large cilia used for transportation. These are the largest cilia any organism uses. Ctenophores lack the ability to sting and instead use tentacles covered by colloblasts . All ctenophores are bioluminescent, meaning they are capable of producing light. Some have the appearance of rainbow coloration. This is caused by the beating of their combs, causing the diffraction of light to form a rainbow. Classification is generally done through comparative morphology.

Morphology Most ctenophores are round or spherical in body shape. They generally have two large tentacles and eight rows of comb plates. Their tentacles have the adhesive colloblasts to capture prey and they have a stomach, mouth, pharynx, and anal pores. They have a nerve network that is rather complex and an apical sense organ. All ctenophores are hermaphrodites and most reproduce sexually. They generally range in size from .6 cm to 30.5 cm.