Sponges, Cnidarians, Flatworms, Roundworms

Ch 26Turboblast Version

Sponges• Aquatic, sessile, asymmetrical, filter-feeding invertebrate• Lack tissues, organs, organ systems (simple bodies)• Osculum- expels water and wastes at the top of sponge (a little like a smoke

stack)• Sponges are made of 4 types of cells:

– Pore cells (surround pores)– Collar cells (line sponge interior, each have a flagellum that creates water current

pulling water into sponge body)– Epithelial-like cells (contract in response to touch)– Amoebocytes (carry nutrients, aid in reproduction, produce chemicals that make

spicules)• Spicules are small, needlelike structures between cells that form hard support

systems• Reproduce sexually/asexually (budding, fragmentation, gemmules/internal buds

made in response to danger)• Hermaphroditic (can create male and female gametes): release sperm into

water, retain eggs within body, fertilization is internal• Larvae swim from the body and land elsewhere, set up camp!

http://youtu.be/RmPTM965-1c

Osculum

Cnidarians (“Nigh-dare-ee-uhns”)(Hydras, Jellyfishes, Corals, Anemones)

• All radially symmetrical, aquatic, invertebrate• 2 basic forms (medusa, polyp)

http://www.infovisual.info/02/img_en/013%20Life%20cycle%20of%20a%20jellyfish.jpg

• Sting prey with cells called nematocysts located on tentacles– Resemble tiny harpoons, inject neurotoxins into prey http://youtu.be/BpKKGB-ivQo, http://

youtu.be/6zJiBc_N1Zk

– digest food within central gastrovascular cavity• Tentacles- ring of flexible, tubelike structures surrounding mouth; used to

capture food • Reproduce both sexually/asexually (budding)

– Sexually- release eggs/sperm into water, external fertilization• Nervous system composed of net of neural tissue (highly-connected network, no

centralized brain tissue)• Hydrozoans (hydras) http://

www.youtube.com/watch?v=yqXkaZwiu6s&feature=share&list=PL9AA335CF2AC21D2F

• Scyphozoans (jellyfishes) http://youtu.be/GqdvEhI1RS0

• Anthozoans (corals and anemones) http://youtu.be/SV06sxvLx2U – [Antho- means “flower”]

hydra

jellyfish

coral

sea anemone

Flatworms• Acoelomates with thin, solid bodies• 3 classes: free-living planarians http://youtu.be/DuwDJ-eZOMc, parasitic flukes

http://youtu.be/_IC9hLsjafw, and tapeworms http://youtu.be/KWaYFC4bqL0

• Simple nervous and muscle systems• Flukes and tapeworms have adapted structures for parasitic lifestyle• Clearly defined head- senses and responds to environment• Pharynx- muscular tube that can extend out of the mouth• Eyespots- sensitive to light, enable worm to respond to light

conditions (cannot see in detail or strong contrast)• Sensory cells located on each side of the head, can detect

chemicals, food, movements in environment• Flame cells- remove excess water

– (much like contractile vacuoles in paramecia; must bail out water that is constantly diffusing into cells)

tapeworm

Complex mouthparts on tapeworm head

planarians

flukes

Roundworms• Pseudocoelomate, cylindrical worms, lengthwise muscles (can

wriggle), relatively complex digestive system, two body openings• Can be parasites of plants, fungi, animals (and humans)• Ascaris in tropical regions, found in soil, enter through mouth,

eggs hatch in intestines, move into bloodstream, then to lungs, then eggs are coughed up (most common roundworm infection in humans)

• Pinworms most common in US, mostly in children, eggs can survive weeks on surfaces, eggs are ingested—worms mature in intestinal tract—females exit host’s anus while host is sleeping and lay eggs on surrounding skin

• http://youtu.be/PrUlhufWlIA

• Can cause trichinosis (ingesting undercooked, infested pork meat)

• Also known as nematodes

pinwormReplica of roundworm mouth