Digestion in Animals – Part 1

1. Digestion in Animals – Part 1

2. All Living things get food somehow • Most unicellular organisms, like bacteria, secrete enzymes and absorb nutrients. • However, In the Protist Kingdom, unicellular organisms are very specialized to obtain food. • Ingestive heterotrophs or autotrophs

3. Amoeba

4. Paramecium structure Oral groove

5. euglena

6. Fungi Kingdom • Secrete enzymes then absorb nutrients – decomposers. Absorptive Heterotrophs

7. Animal Kingdom • There is an increasingly complex system that allows animals to obtain nutrients from food. • Ingestive heterotrophs

8. All animals eat; all animals poop (eliminate undigestible material)!

9. Simple animals have simple methods of getting and using food • Porifera: filter feeder – no digestive system Water & waste amebocyte Collar cell Epidermal cell Water & food flagellum Collar cell Spicule Incurrent pore food nucleus

10. Phylum Cnidaria (formerly called Coelenterata) • All have stinging cells (cnidocytes) • Two body forms: • Medusa – like a jelly fish • Polyp – like a hydra • Radial symmetry • Have tentacles

11. Cnidarian Cnidocyte Have you ever been stung by jellyfish?

12. Cnidarian Life Cycle – medusa and polyp alternate medusa polyp egg larva

13. JELLYFISH - MEDUSAS

14. Hydra Hydroid Polyp body form

15. Hydra on water plants

16. Hydra Anatomy mouth tentacles testis bud Gastrovascular cavity ovary Basal disc

17. Digestion in cnidarians Extracellular – occurs In gastrovascular cavity - enzymes are released from cells lining cavity and food is digested within the cavity. - Nutrients are absorbed by cells in cavity and waste is expelled out the mouth (yuch!).

18. Coral is actually a colony of polyps, most of which are the size of a single hydra – they just make a case around them for their home.

19. Here are a variety of anemones – polyp body form

20. Phylum - Platyhelminthes • Have flat bodies • Some are parasitic • Most are free-living

21. These are free-living flatworms Planaria

22. Tapeworms – the ultimate parasite – the only highly developed system is its reproductive system – hermaphroditic Digestion– absorbs host’s already digested food. Scolex – head with hooks and suckers

23. Phylum Nematoda - roundworms • Body rounded • Tube-within-a-tube body format • Mouth – digestive tube – anus –more efficient – can have specialized organs along the way • Most free-living • Some parasitic

24. Look like threads in the microscope

25. Hookworm Enters through soles of feet Larvae in human feces Causes fatigue – may cause physical and mental retardation if children have it Trichina From undercooked pork Causes severe muscle aches when larvae migrate from intestine to muscles Some are parasitic to humans • Filaria • Causes elephantiasis • No treatment • Carried by mosquitoes

26. This lesion is caused by a nematode infestation

27. Elephantiasis • Caused by filaria – the worm blocks the lympatic vessels and the area swells with lymph. • No treatment is available • (except amputation)

28. Phylum Annelida • Segmented worms • Includes earthworms and leeches • Most are free-living • Complex body with organ systems • hermaphroditic

29. Leech Earthworm Eats dirt Eats blood

30. Earthworm Anatomy

31. Earthworm eats dirt • Pathway of food : Mouth pharynx esophagus crop gizzard intestine anus 1 2 3 4 5 6 7 7 6 1 5 4 3 2

32. Earthworm help the environment by: • Adding nutrients to soil • Aerating soil • Helping get rid of dead organic matter

33. Phylum Mollusca • Soft-bodied animals • All have the same kind of larva • Three types • Gastropods – stomach-footed • Snails and slugs • Cephalopods – head-footed • Octopus and squid • Pelecypods – hatchet-footed • Clams, mussels, oysters, scallops

34. snail slug squid clam octopus slug

35. Digestion in Mollusks Clams: Mucus-feeders Trap food in Mucus on gills Then swallows Both food and mucus

36. Octopus and squid catch live prey using their tentacles and eat them

37. Snails scrape food off surfaces using their radula

38. Phylum Echinodermata • Spiny skinned animal • Starfish • Sand dollar • Sea cucumber • Turn stomach inside out to eat – stomach gives off digestive juices and the digested mess is swallowed along with the stomach when it is brought back into the body. • Radial symmetry – no head, tail, front or back • Move using tube feet – part of water vascular system

39. Sea urchins, sand dollars, and starfish

40. Phylum Arthropoda • Jointed legs • Chitinous exoskeleton • Ventral nerve cord • Must molt to grow • Some undergo metamorphosis • Includes insects, crustaceans, spiders, millipedes and centipedes, and horseshoe crabs

41. Class Insecta • Six legs • May have wings • Undergo metamorphosis • Varied mouthparts • Breathe using spiracles

42. Some common insects Some of these are insects, some are not…. Can you tell which is which?

43. Class Arachnida – 8 legs, no antennae, simple eyes, chelicerae, scorpion tick Dust mites spiders

44. Class Crustacea – two body regions = cephalothoraxmost live in water

45. Millipedes and Centipedes

46. The end The end