Phylum Porifera - Sponges

1. Phylum Porifera- Sponges • Porifera means “pore-bearer” • Sponges are • Asymmetrical • Sessile • Contain cells only; no tissues • Choanocytes (“collar cells”) are flagellated cells that line the internal cavity of a sponge and aide in filtering food from the water

2. Porifera continued… • As water leaves the sponge, waste products are washed away • Some sponges have skeletons made of spicules • Asexual (budding or fragmentation) and sexual reproduction (hermaphrodites)

3. Phylum Cnidaria- Cnidarians • No brain or central nervous system; have a nerve net instead that aid in muscle contraction • Radial symmetry • Two tissue layers • Endoderm (inner) • Ectoderm (outer) • Sexual (external fertilization) or asexual reproduction (budding)

4. Two basic body forms: • Medusa (free floating umbrella shape) • Polyp (tube-like, usually attached to a substrate) • Tentacles surround the opening of the gastrovascular cavity • Each tentacle contain stinging cells called cnidocytes • Within each cnidocyte is a small, barbed harpoon called a nematocyst • Used for defense and to spear prey • Some contain toxins that kill or merely stun • The tentacles bring the prey into the gastrovascular cavity

5. 3 Types of Cnidarians • Hydrozoa—ex. Hydra • Include polyp and medusa stages • Attached to substrates by an area on their body called a basal disk • Scyphozoa—“true jellyfish” • Active predators • Mostly medusa stage but also have a polyp stage • Anthozoa—exist only as polyps • Sea anemones and corals • Most have a symbiotic relationship with protists

6. Phylum Platyhelminthes “Flat Worms” • Defined head and tail region • Centralized nervous system containing a brain and nerve cords • Eyespots for light detection • Bilateral symmetry • 3 tissue layers • Mesoderm is middle tissue layer that helps form true organs • Gastrovascular cavity

7. More on Flatworms • Flatworms are hermaphroditic and capable of sexual and asexual reproduction • Passive diffusion through the skin supplies oxygen to their body parts • Most species of flatworms are parasitic Planaria

8. Tapeworms and You! • Generally infect vertebrates or humans • Suckers and hook-like structures allow the tapeworm to permanently attach themselves to the inner wall of their host’s intestines • Food is directly absorbed from the host’s intestines to the tapeworm’s skin • Grow by producing a string of rectangular body sections called proglottids behind their head • May grow up to 40 ft long!

9. Largest flatworm class consisting of parasitic worms called flukes • Most have complex life cycles • Some live inside their hosts making them endoparasites or outside their host making them ectoparasites • Flukes do not have a well-developed digestive system because of its dependence on a host

10. Phylum Nematoda “Round worms” • 3 tissue layers • Gases are exchanged through the fluid by diffusion • Simplest animals to have a one-way digestive system • Have long muscles that extend the length of the worm • Allows the nematode to move whip-like • Many cause human and plant diseases

11. Roundworms and your pet!

12. Roundworms: Guinea Worms A Worldwide Problem • What is dracunculiasis? • Dracunculiasis, more commonly known as Guinea worm disease (GWD), is a preventable infection caused by the parasite Dracunculus medinensis. Infection affects poor communities in remote parts of Africa that do not have safe water to drink. • How does Guinea worm disease spread? • Adult female Dracunculus worms emerge from the skin of Infected persons annually. Persons with worms protruding through the skin may enter sources of drinking water and allow the worm to release larvae into the water. These larvae are eaten by fresh water “water fleas” where these develop into the infective stage in 10-14 days. Persons become infected by drinking water containing the water fleas that have the infective stage larvae of Dracunculus medinensis.

13. Roundworms: Pinworms and You! • What are the symptoms of a pinworm infection? • Itching around the anus, disturbed sleep, and irritability are common symptoms. If the infection is heavy, symptoms may also include loss of appetite, restlessness, and difficulty sleeping. Symptoms are caused by the female pinworm laying her eggs. Most symptoms of pinworm infection are mild; many infected people have no symptoms. • Who is at risk for pinworm infection? • Pinworm is the most common worm infection in the United States. School-age children, followed by preschoolers, have the highest rates of infection. In some groups nearly 50% of children are infected. Infection often occurs in more than one family member. Adults are less likely to have pinworm infection, except mothers of infected children. Child care centers, and other institutional settings often have cases of pinworm infection. • Danger of Sandboxes!

14. Roundworms: Elephantiasis • What is lymphatic filariasis? • Lymphatic filariasis is a parasitic disease caused by microscopic, thread-like worms. The adult worms only live in the human lymph system. The lymph system maintains the body's fluid balance and fights infections. • How is lymphatic filariasis spread? • The disease spreads from person to person by mosquito bites. When a mosquito bites a person who has lymphatic filariasis, microscopic worms circulating in the person's blood enter and infect the mosquito. People get lymphatic filariasis from the bite of an infected mosquito.

15. Phylum Annelida “Segmented worms” • Easily recognized by their segments which are in ring-like structures • Each segment contains digestive, excretory, circulatory, and locomotor organs • Simple brain located in head region • Digestive tract

16. Have circular and longitudinal muscles which allow the worm to crawl • Circular muscles contract to elongate the segment • Longitudinal muscles contract to bunch up the segments • Respiration occurs through the worm’s skin • The digestive tract is divided into different regions for different functions of digestion • Have external bristles called setae • Located on each segment to increase traction • Earthworms are hermaphrodites

17. Examples include polycheates, leeches and earthworms • Earthworms eat detritus using this pathway: • Muscular pharynx, esophagus, crop, gizzard, intestine, anus • Leeches have suckers at both ends of their body

18. Phylum Mollusca “Soft-bodied” • FYI: Second largest animal phyla • Examples: snails, slugs, oysters, clams, scallops, octopuses, and squid • Aquatic mollusks have gills for respiration, terrestrial mollusks have thin membranes that act as a primitive lung or do respiration through their skin • Sexual reproduction

19. Key characteristics shared by all mollusks • All have: • Bilateral symmetry • Digestive Tract • Three-part body plan • Visceral mass—a central section that contains the mollusk’s organs • Mantle—a heavy fold of tissue that wraps the visceral mass like a cape • Secretes a shell in some mollusks • Foot—muscular region which is used primarily for movement or grasping • Many have a radula—a rasping tongue-like organ located in their mouth

20. Gastropods Ex. Snails, slugs, nudibranchs • Foot is adapted for locomotion • Have various feeding habits mainly using their radulas • Bivalves Ex. Clams, oysters, mussels • Most are sessile but some like scallops will flap its valves to move • Most bivalves are filter feeders

21. Cephalopods (squids, nautiluses, octopuses) • Large head attached to tentacles (foot divided into parts) • Squid (10 tentacles), octopus (8 tentacles), nautilus (80-90 tentacles) • Nautilus only living cephalopod with a shell • Most intelligent of all invertebrates • Have eyes similar to vertebrates’ eyes • Have the largest eyes known in any animal • Move by closing their mantle cavity to shoot water out forcefully • All cephalopods are active marine predators feeding on fish, mollusks, crustaceans, and worms

24. FYI—Pearls • Many species of bivalves produce pearls • When a grain of sand becomes stuck between a mollusk’s mantle and shell, the mollusk coats the sand with nacre • Nacre is also mother-of-pearl that is also used on the inside of the bivalve’s shell • The sand is continually covered in nacre to form a pearl • Only pearls that contain overlapping mineral crystals within the nacre are considered gem-quality pearls

25. Phylum Arthropoda • FYI: Means “jointed foot” • FYI: Over 1 million species • Most diverse group of animals • Most have: • Segmented bodies • Usually in three distinct regions: head, thorax (mid-body region) and abdomen • The head may fuse with the thorax to form a cephalothorax • Exoskeleton made of protein, chitin • Prevents water loss, protects internal structures, and attachment for muscles • Does not grow with organism, so they must shed their exoskeleton—molting

26. More common characteristics • Appendages: legs, antennae, mouthparts etc… that grow out from the body and are jointed/bendable • Open circulatory system • Air enters spiracles through a network of fine tubes called tracheae • Distinct head often with compound eyes • Eye made of thousands of individual units each with its own lens and retina • Image is not as clear but motion is detected more quickly

27. Chelicerata • Spiders, scorpions, ticks, mites, marine horseshoe crabs, sea spiders, and harvestman (daddy long legs)‏

28. Chelicerata • Chelicerae are mouthparts modified into fangs • Arachnid body • Cephalothorax • Abdomen • No antennae • Chelicerae, first pair of appendages • Second appendage, pedipalps modified to catch and handle prey • Four functioning legs • All arachnids are carnivorous except mites • Spider—produce silk through spinnerets • Scorpions—stinger-tipped abdomen • Mites—single, unsegmented body

29. Crustaceans • Crabs, lobsters, crayfish, shrimps, barnacles, water fleas, Daphnia, pill bugs, etc…

30. Crustaceans • Gills • Cephalothorax with protective shield—carapace • In crayfish and lobsters, anterior pair of legs is modified into large pinchers called chelipeds • Barnacles are sessile crustaceans with a free-swimming larval stage • Reproduction: mainly sexual with internal fertilization • Sperm is deposited where eggs are released, no water required

31. Diana Butterfly Praying Mantis Uniramia (Insecta, Diplopoda, Chilopoda)‏ • Butterflies, beetles, fleas, lice, grasshoppers, ants, mosquitoes, etc…

32. Bald-faced Hornet Insecta • Chewing mouthparts—mandibles • Most have: • Head-mandibles, one pair of antennae, compound eyes • Thorax-composed of three fused segments, two or three pairs of jointed legs attached • Abdomen-composed of 9-11 segments • First animals to evolve wings • Insect life cycle • Complete metamorphosis • Egg, larva, protective capsule stage chrysalis, pupa, adult • Incomplete metamorphosis • Egg, nymph, after several molts becomes adult

33. Developmental Patterns • Protostomes—develop a mouth first and anus second from the opening of the digestive cavity • Nematodes, Annelids, Mollusks, Arthropods • Deuterostomes—develop an anus first and a mouth second • Echinoderms

34. Phylum Echinodermata- Sea stars, sand dollars, sea cucumbers, sea urchins • “Spiny skin” • All marine • Bilateral larvae then 5-part radial symmetry as adults • Number of arms can vary

35. Calcium-rich endoskeleton composed of individual plates called ossicles • Even though the ossicles of adult echinoderms appear to be external, they are covered by a thin layer of skin • No head or brain • Nervous system consists of a central ring of nerves with branches extending into each of the arms • Regeneration of arms • Water vascular system—water-filled system of interconnected canals and thousands of tiny hollow tube feet • Tube feet extend outward through openings in the ossicles • Used for locomotion, feeding and gas exchange

36. Sea stars • Most are carnivores • Responsible for the mass destruction of coral polyp colonies • Brittle stars • Name given for the delicacy of their brittle arms • Most are filter feeders • Sea lilies and feather stars • Most ancient and primitive echinoderms • Sessile

37. Sea urchin and sand dollars • Lack arms but still have the 5-part body plan • Some sea urchins contain venom • Sea cucumbers • Soft-bodied, slug-like animals without arms • Ossicles are small and not fused • Sea daisies • Only two known species of newly discovered group • No arms but still have 5-part radial symmetry