Back to Chapter 7

1. Back to Chapter 7 The Marine Worms

2. So far, this chapter… • Marine animals without a backbone • Vertebrates vs. invertebrates • Vertebrates have a backbone (a row of bones called vertebrae) • 97% of all animal species are invertebrates • Animals • Multicellular • Cannot manufacture own food

3. Porifera - Sponges • Sessile • Filter feeders • No true tissues or organs • Suspension feeders(eat food particles suspended in water) • Filter feeders )actively filter food particles

4. Types of Symmetry (Body Types)

5. Cnidarians: Radial symmetry • Phylum Cnidaria • Also called coelenterates • Oral surface and aboral surface • Nematocysts (stinging structures found in cnidocysts) • Two forms: polyp and medusa • Two layers of cell form a body wall • Epidermis external • gastrodermis lines gut • with gelatinous mesoglea in between

6. Types of Cnidarians • Hydrozoans –sessile, feathery or bushy colonies of tiny polyps • Siphonophores – hydrozoans that form drifting colonies of polyps • Scyphozoans – larger jellyfish • Large bell, swim with rhythmic contractions of the bell • Anthozoans –lack a medusa stage • Sea anemones, corals, gorgonians

7. Ctenophora • Comb jellies • Radial symmetry • Eight rows of ciliary combs • Capture prey using two long tentacles • Sticky cells named colloblasts

8. Worms, Worms, Worms!

9. What are worms? • Commonly, animals with long, thin bodies and no legs • Bilaterally symmetrical invertebrates

10. Why bilateral symmetry? • Allows animals to be more active • To capture prey • To develop sophisticated behaviors • Implies development of an anterior end with a head, brain, and eyes.

11. Main groups of marine worms: • Flatworms • Ribbon worms • Nematodes - roundworms • Segmented worms : • Annelids • Polychaetes • Oligochaetes • Leeches • Peanut worms • Echiurans • Arrow worms – chaetognaths • Acorn worms

12. Flatworms: Platyhelminthes • Dorsoventrally flattened • Simplest animal with tissues organized into real organs and organ systems • Brain and central nervous system • Only one opening to gut • No body cavity

13. Flatworms

14. Flatworms • Flukes or trematodes • All are parasitic • In fish, seabirds, whales • Tapeworms or cestodes • Body in repeated units • Lack a mouth or gut • Found in sperm whales,fish

15. Parasites in local fish http://www.dfg.ca.gov/marine/parasites.asp

16. Ribbon worms: Nemertea • More complex than flatworms • Complete digestive tract • Gut with mouth and anus • Closed circulatory system • Proboscis • Used to entangle prey • Secretes toxins, may have a spine • 5mm- 30 m in length!

18. Nematodes • Roundworms • Pseudocoelem • Tube-within-a-tube body plan • In sediments • Some parasitic • Seals, dolphins • Risk in sashimi, ceviche • Small, slender, cylindrical bodies • Gut, ends in anus • Lies within a body cavity • Hydrostatic skeleton

19. Roundworm life cycle

20. Body cavity development Flatworms Roundworms

21. True coelom • Segmented worms • Humans • Gut lies in the coelom

22. Segmented worms: Annelida • Earthworms and marine worms • Body consists of similar segments • Gut goes through all segments • Gut lies in coelom • Hydrostatic skeleton • Longitudinal and circular muscles • Efficient crawlers and burrowers • Longitudinal muscles lengthen and shorten segments • Circular muscles increase or decrease diameter. • Closed circulatory system • Respiration by diffusion bristleworm

23. Polychaetes • All marine annelids are polychaetes • Each body extension has a pair of parapodia • Flattened extensions • May be stiff, sharp bristles or setae Annelida, Christmas tree worm

24. Polychaete variety • May burrow • May crawl • May live in tubes • May be planktonic • Palolo worm • Swarming • Timed by moon cycle • Bottom half of body breaks off and swims to surface to spawn. • Trochophore – planktonic larval stage

25. Leeches • Blood sucking parasites that attach to marine fish and invertebrates

26. NOT Worms? • Larval stages: grubs, caterpillars, maggots • Legless amphibians and reptiles • Insects • Centipedes Anguis, or slow worm centipede Grubs: beetle larvae

27. Marine Worms • Annelida (segmented worms) • Chaetognatha (arrow worms) • Gnathostomulid (jaw worms) • Hemichordata (acorn/tongue worms) • Nematoda (roundworms) • Nematomorpha (horsehair worms) • Nemertea (ribbonworms) • Onychophora (velvet worms) • Phoronida (horseshoe worms) • Platyhelminthes (flatworms) • Priapulida (phallus worms) • Sipuncula (peanut worms)

30. Sipuncula – peanut worms • Some burrow in mud or rock • Some live in crevices • Shaped like a peanut • Unsegmented. • Intestine forms a loop • Retractable forward section, called the introvert • No circulatory or respiratory systems • 1-35 cm long

31. Echiura Soft, unsegmented, sausage-like Like sipunculans, except for a non-retractable, spoon-like or forked proboscis Deposit feeders Proboscis gathers organic material The “fat innkeeper” lives in mud in a U-shaped tube.

33. Arrow worms - Chaetognatha • All marine. • Planktonic. • Transparent. • Fish-like tail and fins. • Head with eyes, grasping spines and teeth. • 4mm-10cm in length. • Hermaphrodites. • Remain motionless and then dart rapidly toward prey.

34. Acorn worms - Hemichordata • Evolutionary link between Echinoderms and Chordata • Dorsal, hollow nerve cord • Openings along the anterior of the gut, gill slits, • Body in three parts • Worm-like deposit feeders • Live free or in U-shaped tubes • Use a thick, muscular proboscis to collect organic material from sediment

36. Sea worm is a general term that may refer to a number of phyla of animals, or may refer specifically to: • Acanthocephala, parasitic worm • Annelida, segmented worms • Chaetognatha, arrow worms • Cycliophora, lobster worms • Entoprocta • Echiura, spoon worms • Gastrotricha, microscopic • Gnathostomulida, microscopic • Hemichordata • Kinorhyncha • Loricifera • Micrognathozoa, microscopic • Nematoda, round worms • Nematomorpha, parasitic worms • Nemertea, ribbon worms • Phoronida, horseshoe worms • Platyhelminthea, flatworms • Priapulida • Sipuncula, peanut worms • Xenoturbellida