Team Two!!! w Platyhelminthes (flatworms) w Rotifera (rotifers) and Nematoda (round worms) w Nemertea (ribbon worms) and Lophophorate

Platyhelminthes w Have bilateral symmetry w Can be free living or parasitic which absorb nutrients from a host w Have 3 germ layers and are acoelmate (lacking a cavity between gut and outer wall) w Are protostomes w Move by using cilia or by contracting their muscles Flatworm

Platyhelminthes w Free living platyhelminthesreproduce asexually by fission and parasitic platyhelminthes reproduce sexually and self fertilize w The embryo of tapeworms and other parasitic worms are called scolex Tapeworm

Platyhelminthes w - Trichinella Life cycle w Schistosoma Life Cycle-

Platyhelminthes w Specalized Tissues Platyhelminthes have a ventral nerve cord have eye spots that detect the intensity of light have ganglia, which is a mass of nerve cell bodies ( resembles a brain) have a gastrovascular cavity called a pharynx- which is a single opening used as both a mouth and anus w Examples are tapeworms, flukes, Dugesia, Dugesia tigrina

Phylum Rotifera w About 1,800 species w Are tiny animals that mainly inhabit fresh water, although some live in the sea or in damp soil. w Range in size from about 0.05 to 2 mm (much smaller compared to other protists.) w Have bilateral symmetry and are truly multicellular. w “Rotifer,” derived from Latin, means “wheel-bearer”—a reference to the crown cilia that draws a vortex of water into the mouth. w Examples: Rotaria, Philodina, Keratella, Brachionus, and Polyarthra.

Phylum Rotifera w Have specialized organ systems—including a complete digestive tract: a digestive tube with a separate mouth and anus. w Perform a type of reproduction called parthenogenesis: females producing more females from unfertilized eggs.

Phylum Rotifera w Are pseudocoelomate animals—they have a cavity that is not completely lined by mesoderm-derived tissue. w The fluid in the pseudocoelom serves as a hydrostatic skeleton and as a medium for the internal transport of nutrients and waste. w Rotifers may be: -free swimming -able to move by inchworming along the substrates -sessile, living inside tubes or gelatinous holdfasts. w Video:

Phylum Nematoda w Roundworms w About 90,000 known species. w Many are free-living soil dwellers that help decompose and recycle nutrients. w Have bilateral symmetry. w Examples: whipworms, hookworms, pinworms, ascarids, and filarids. Nematoda

Phylum Nematoda w Have a complete digestive tract: a digestive tube with a separate mouth and anus. w Covered by a tough, transparent cuticle—the exoskeleton of an arthropod, consisting of layers of protein and chitin. w The muscles of nematodes are all longitudinal, and their contraction produces a thrashing motion. This and the cuticle help nematodas to move. w Are pseudocoelomate animals— they have a cavity that is not completely lined by mesoderm- derived tissue.

Phylum Nematoda w Reproduction is usually sexual—females are generally larger than males. w Fertilization is internal, and a female can deposit 100,000 or more fertilized eggs per day. w The zygotes of most species are resistant cells capable of living in harsh conditions. Hookworm

Phylum Rotifera and Nematoda w Are both eumetazoa—they have closely functioning cells organized into tissues. w They are triploblastic (contain three germ layers.) These three layers (ectoderm, mesoderm, and endoderm) develop into various organs during embryonic development. w There is a progressively greater increase in nerve tissue concentration at the anterior end (head.) w Both have a complete digestive tract.

Nemertea w Many live in water, so they can swim quite well. w Has a complete digestive tract and a closed circulatory system. (blood contained in vessels) w However, they have no heart, the blood is propelled by muscle squeezing vessels. Baseodiscus delineatus -The phylum has bilateral symmetry -Has 3 germ layers -Has a primitive coelom. -They use the coelom (filled with fluid) to propel themselves through the water.

Nemertea (cont.) w Life: As a juvenile the nemertea lives in the exoskeleton of a crab. The size increases as the crab’s shell increases. They are predators and will either actively pursue their prey or sit and wait for it. Cerebratulus

Nemertea (cont.) w Examples: Malacobdella lives parasitically in molluscs Tubulanus rhabdotus Deep water ribbon worm. The proboscis apparatus is used as a means of catching food. It wraps around the food and draws it in.

Nemertea (cont.) w Different types of Nemertea have different colors, however their colors change depending on where they are. (caves or exposed). w Commonly called ribbon worms. w The largest type of Nemertea that has been found, Lineus longissimus, stretched 30 m long! w Normally 10mm- 100cm long.

Removal of Guinea Worm

Lophophorate w Combines three phyla: Bryozoans, Phoronids, Brachiopods. w All three have a lophophore: a horseshoe-shaped fold of the body that has cilia, surrounding the mouth. w The three phyla also share a U-shaped digestive tract and have no head. Bryozoan

Lophophorate (cont.) w They have true coeloms, lined fully with mesoderm. 3 germ layers. w Bryozoans and brachiopods are sessile while phoronids live buried in the sand. w Development: Bryozoans- larval; has radial clevage at first, and then spiral. w Placed closer to protostomes, however in embryonic development they resemble deuterostomes.

Lophophorate (cont.) Costazia costazi, bryozoan Fresh water Bryozoan with lophophore extended. Phoronopsis californica- phoronid Phoronis hippocrepia - phoronid Onniella meeki- Brachiopod

Lophophorate (cont.) w Bryozoans help build reefs w Brachiopods, resemble clams. w Phoronids- tube- dwelling marine worms. Tubes made of chitin! w Seem to be either asymmetrical or bilateral.

Review Game: Platyhelminthes w What type of symmetry do Platyhelminthes have? w How do Platyhelminthes move? w How do parasitic platyhelminthes reproduce? w What is the function of eye spots?

Answers: Platyhelminthes w What type of symmetry do Platyhelminthes have? Bilateral Symmetry w How do Platyhelminthes move? By using cilia or by contracting their muscles. w How do parasitic platyhelminthes reproduce? They reproduce sexually and self fertilize. w What is the function of eye spots? They detect the intensity of light.

Review Game: Rotifera and Nematoda w What type of symmetry do the phylum Rotifera and phylum Nematoda share? w What is a complete digestive tract? w What type of reproduction do Rotifers perform? w Which phylum has a hydrostatic skeleton?

Answers: Rotifera and Nematoda w What type of symmetry do the phylum Rotifera and phylum Nematoda share? Bilateral Symmetry w What is a complete digestive tract? A digestive tube with a separate mouth and anus. w What type of reproduction do Rotifers perform? Parthenogenesis w Which phylum has a hydrostatic skeleton? Rotifera

Review Game: Nemertea and Lophophorate w What are the three phyla under lophophorate? And what do they look like? w What is a proboscis apparatus? w Where do nemerteas grow up? w What is the function of Bryozoans?

Answers: Nemertea and Lophophorate w What are the three phyla under lophophorate? Bryozoans, Phoronids, Brachiopods And what do they look like? All three have a lophophore. w What is a proboscis apparatus? It is used as a means of catching food. It wraps around the food and draws it in. w Where do nemerteas grow up? In the exoskeleton of a crab. w What is the function of Bryozoans? They help build reefs.

~THE END~