Porifera, Cnidaria, and Flatworms

Levels of Organization All animals are multicellular – made of more than 1 cell Animals can be organized on the cellular, tissue, or organ level of organization. Cell – Sponge Tissue – Jellyfish - Have endoderm & ectoderm only Organ – Worms - Have ectoderm, endoderm, and mesoderm

Type of Body Plan Two body plans are present in the animal kingdom: Sac plan: Incomplete digestive system with only one opening. Ex: Jellyfish & planaria

Tube-within-a-tube plan: Complete digestive system. Two openings allows for specialization along the length of the tube. Ex: Roundworms, earthworms, insects

Type of Symmetry Three types: Asymmetrical animals have no particular symmetry. Radial symmetry means the animal is organized similar to a wheel. Bilateral symmetry means the animal has definite right and left halves.

Type of Coelom Coelom - an internal body cavity where internal organs are found. Ex: Mollusks, annelids, echinoderms, vertebrates Pseudocoelom - a body cavity incompletely lined with mesoderm. Ex: Roundworms, rotifers Acoelomates - have mesoderm but no body cavity. Ex: Flatworms, sponges, jellyfish

Segmentation Segmentation is the repetition of body parts along the length of the body. Animals can be segmented or nonsegmented. Segmentation leads to specialization of parts. Ex: annelids, arthropods, and chordates (includes vertebrates).

Phylum Porifera - Sponges Meaning: Pore-bearing Symmetry – none (asymmetrical) Organization – cellular level Acoelomates – no body cavity (so no organs) Non-segmented Habitat – fresh & salt water

Anatomy (see below and on next slide)

Flagella Filaments Collar cell Internal cavity Epidermis Flagella Osculum Amebocyte Collar cell Pore channel Pores Spicules

Anatomy Epidermis – found along outer body wall Amoeboid cells (amebocytes) – middle layer Transport nutrients Produce spicules Form sex cells Collar cells - inner layer – digest nutrients Collar cells contain the following: Flagella - pull water in through pores and circulate water though the sponge Filaments - trap food particles.

Life processes Sponges are classified according to type of spicules Support - spicules (act like bones for the sponge) Diet - filter feeders – filter bacteria, protists, and sometimes small crustaceans Feeding – –Filaments trap food –Collar cells digest food

Movement: - Swim as larva - Sessile (permanently attached to a surface) as adults. Response - no nervous system. Excretion - through the osculum. Respiration - take in oxygen as water passes through body – diffusion.

Reproduction – Hermaphrodites (make eggs & sperm). Asexually by: Budding: Produce internal buds that can grow into new sponges when the conditions are more favorable Regeneration: Growth of a whole organism from a fragment

Sexually: Release sperm into the water Sperm enters pores of another sponge of same species Fertilizes egg within Larva released through osculum (see life cycle diagram next slide). Poor reproductive odds!!!

Sperm 2.Egg 3.Dividing cells (spongocoel) 4.Larva 5.Larva released 6.Flagella (moves) 7.New sponge develops

Phylum Cnidaria Named for – specialized stinging cells called cnidocytes (contain the stingers called nematocysts – these may contain poison) Symmetry – radial Organization – tissue level Acoelomates – no body cavity (so no organs) Non-segmented; sac body plan Habitat – mostly salt water, hydra found in fresh water

Body forms: may be a polyp or a medusa, or may alternate between the two forms. Polyp – tentacles up, usually sessile Medusa – tentacles down, usually active

Examples of animals – Sea anemone – solitary polyp, very colorful Coral – some solitary, most colonial, polyp form, calcium carbonate skeleton, form reefs Portuguese man-of-war – colony of polyp & medusa individuals, each with specialized jobs such as feeding & reproduction Jellyfish – medusa, can live at great depths Hydra – freshwater, polyp form, commonly attached to underwater rocks or plants, less than 1cm in length

Basal disc Ovary Developing egg Sperm Testis Bud GVC – Gastrovascular cavity Endoderm Ectoderm---- Stinging capsule Tentacle Mouth

Anatomy Sac body plan – single opening serves as mouth and anus Outer tissue layer – ectoderm Inner tissue layer – endoderm Mesoglea – jelly-like material that separates above 2 tissue layers Muscle fibers running in 2 directions Tentacles surround mouth Large space inside called gastrovascular cavity (GVC)

Life processes Movement: Directional Move by contraction & expansion of body Tentacles can grab prey Response: Nerve net – interconnecting nerve cells and communicate with sensory cells throughout body (think of a basketball net)

Support Hydrostatic skeleton –fluid-filled closed chambers

Diet – protists and small animals Feeding – Sting prey with nematocysts (stingers) Stuff food into mouth using tentacles Don’t chase their prey – but movement of medusa can help drawn food in towards body. Food passes into GVC (gastrovascular cavity) Digestion – by cells of endoderm

Internal transport: Nutrients and oxygen pass from cell to cell through the process of diffusion Respiration: Diffusion between ectoderm & water. Excretion: Wastes are excreted through the mouth

Reproduction: Usually appear as separate males & females Sexual reproduction – see life cycle diagram given separately Jellyfish – Release eggs & sperm into water Swim as larva, settle as polyps, then divide to become medusa Several young from one fertilized egg Hydra – release egg or sperm from body wall; meet, swim as larva, settle as polyp

Medusa Polyp Planula Blastula Egg Sperm

Asexual reproduction Budding – cluster of cells form, break off, grow into adults Regeneration – fragments develop into new animals

Phylum Platyhelminthes Meaning – flatworms Symmetry - bilateral Sac body plan Non-segmented Acoelomates Organization – organ level Have organs for all life processes except respiration and circulation Habitat – fresh or salt water, moist environments, inside host

Examples: Marine flatworms Tapeworms Freshwater planarians Flukes

Planarians - Lifestyle - free-living Habitat - freshwater Movement – secrete slime, push through with cilia, muscles Excretion – flame cells – interconnecting canals throughout body Response - small brain - ladder of nerves - light-sensitive eyespots - Auricles sensitive to chemicals Respiration - diffusion

Internal transport - diffusion Diet – plankton (small worms or crustaceans) Feeding – wrap around prey - secrete slime - extend pharynx to suck up food Digestion – occurs in GVC Gender - hermaphrodites Sexual reproduction – have sex, exchange sperm, each planaria gets pregnant - 2 sets of young hatch from eggs 2-3 weeks later.

Asexual reproduction – capable of regeneration; 1 worm can even grow 2 heads or 2 tails!!

Planarian

Flame cells Excretory pore Flame cells GVC Pharynx Mouth Endoderm Mesoderm Ectoderm GVC Cilia Eyespot Brain Auricle Longitudinal nerve cord Transverse nerve cord

Ovary Oviduct Testes Sperm duct Penis Vagina

Parasitic Flatworms Two classes - flukes and tapeworms Require host to carry on life cycle – see next slide Primary host – infect as adult Secondary host – infect as larval stage Tapeworm – Scolex with hooks and suckers to hold itself inside the gut. No digestive system; absorbs host’s digested food through skin

Body is an assembly line of square sections called proglottids, which contain male and female sex organs. As proglottids mature, they break off, pass with feces, and release eggs. When animals feed in feces-contaminated food, larva eventually form cysts in muscles of secondary host. When humans eat infected meat, larva hatch from cyst, attach to intestine, and grow to adulthood.

1.Hooks 2.Suckers 3.Scolex 4.Neck 5.Proglottids 6.Testes 7.Ovary 8.Eggs 9.Detached proglottid 10.Longitudinal nerve cord 11.Brain (ganglia) 12.Transverse nerve cord

Life cycle:

Contracted by eating undercooked, infected beef, pork, or fish. Transmitted to cats & dogs by fleas that have eaten feces of infected host Primary symptom – weight loss In prolonged infections – worms migrate to eyes, heart, brain, lungs, & liver & form cysts – cause swelling, cramps, diarrhea, anemia, & seizures Diagnosed by fecal exam; treated with medicine

Fluke Have sucker at anterior end to attach to host Various species – can infect digestive tract, bile duct, blood, & lungs. Blood flukes cause schistosomiasis – one of the most common worm infections worldwide (about 200 million in mostly Middle East, Asia, Africa, & S. America) Common in areas with poor sewage treatment Enter through skin when in infected water – see life cycle diagram next slide

Schistosomiasis

Diagosed by fecal exam; treated with medicine Symptoms: nausea, abdominal pain, increased bowel movements, diarrhea, weight loss, fatigue Burrow through host, feed on host’s blood & tissues. Can live for up to 2-3 decades inside host (usually only 5-10 years) Reproduce non-stop – 100 – 300 eggs/day