Animals, Part I Invertebrates

1. Animals, Part IInvertebrates • Introduction to Animals (Chapter 34) • Sponges and Jellyfish (Chapter 35) • Simple Worms (Chapter 36) • Mollusks and Annelids (Chapter 37) • Arthropods (except Insects) (Chapter 38) • Insects (Chapter 39) • Echinoderms (Chapter 40)

2. Animal Features • Animals are: • Eukaryotic • Their cells have proper nuclei, but no cell walls • Multicellular • Most animals have differentiated, specialized tissues. • Heterotrophic • They must get nutrition from other organisms • Most are herbivores (eat plants) or carnivores (eat meat) • But a few are parasites (consume living hosts) or symbiotic (live in mutually beneficial relationship) In addition, most animals are mobile (they can move around, at least during some part of their life) and very responsive (most have a nervous system). Animals range in size from tiny (about a millimetre) to huge (a blue whale is over 30m long)

3. Kingdom Animalia • Part 1. The invertebrate animals

4. The Lower Invertebrates • Phylum Porifera, the Sponges • Phylum Cnidaria, the Jellyfish and corals • Phylum Ctenophora, the comb jellies • Phylum Platyhelminthes, the flat-worms • Phylum Rotifera, the rotifers • Phylum Nematoda, the round-worms

5. Evolution of Invertebrates Protists Echinoderms Sponges Jellyfish Annelids and Arthropods 543 510 439 409 363 290 245 206 144 65 2 Jurassic Ordovician Devonian Carboniferous Triassic Ternary Cambrian Permian Cretaceous Silurian Quaternary

6. Sponges • Sponges look plant-like, but they are in fact animals. • Adult sponges are sessile, that is, they attach to rocks and don’t move around.

7. Sponges feed by filtering food out of the sea water.

8. Jellyfish and Relatives Phylum Cnidaria Phylum Ctenophora

9. Jellyfish, Hydra and Coral (Phylum Cnidaria) • Cnidaria can have two basic body shapes, the “polyp shape” and the “medusa shape” • The two shapes are similar, with tentacles, a mouth opening, an epidermis and a jelly-like mesoglea. • In the “polyp” shape, the tentacles open upwards, • In the “medusa” shape the tentacles hang downwards.

10. Jellyfish are medusa, hydra, coral & sea anemone are polyp

11. Nematocysts (ouch!) • Jellyfish have stinging cells called nematocysts on their tentacles. These can kill or paralyze small prey, allowing the slow-moving jellyfish to consume them. • The Portuguese-man-of-war is a colonial relative of the jellyfish. It can be quite deadly

12. Comb Jellies (Phylum Ctenophora) • A more distant relative of the jellyfish is the elusive comb jelly. • Comb jellies lack stinging cells. • Some display bioluminescence – the ability to glow in the dark

13. Flatworms, Rotifers and Roundworms Phylum Platyhelminthes Phylum Rotifera Phylum Nematoda

14. PlatyhelminthesThe Flat Worms • Flatworms include harmless free-living organisms like the planarian • There are also parasitic flatworms, like tapeworms (cestodes) and flukes (trematodes)

15. Rotifers • Rotifers are microscopic and near-microscopic animals. They may be spherical or worm-like

16. NematodesThe “Roundworms” • Nematodes are cylindrical worms, usually pointed at each end. • They range in size from microscopic to about a meter long. • They include both free-living and parasitic varieties, with the parasitic ones being larger.

17. A microscopic roundworm Warning: close your eyes if you are squeamish! Child infested with ascaris roundworms. It is unusual to see them on the mouth & nose. Usually they come out the other end! Ascaris, a parasitic intestinal roundworm

18. Roundworms & Disease Trichina worm in Muscle • Nematodes cause several diseases • Trichinosis: a disease of the muscles and nerves caused by microscopic worms from uncooked meat (especially pork) • Hookworms: intestinal parasite (cause bleeding) • Pinworms: intestinal parasite (cause itching) • Skin conditions: (worms enter cracks in feet) • Heartworms: (common in dogs, can kill) Pinworms are very common. It is estimated that between 30 and 80 percent of children in North America have been infected by pinworms at some point.

19. The Higher Invertebrate Phyla • Phylum Mollusca, the mollusks • Clams, oysters, snails, slugs, octopus, squid • Phylum Annelida, the segmented worms • Earthworms, seaworms, leeches • Phylum Arthropoda “arthropods” The joint-legged invertebrates. • Crustaceans, insects, arachnids • Phylum Echinodermata, the echinoderms • Starfish, sand-dollars, sea urchins, sea cucumbers

20. Mollusks Phylum Molluska

21. Mollusks • There are three main types of mollusk • Bivalves (clams, oysters, scallops etc) have two shells surrounding the soft mollusk inside • Gastropods (snails, sea-snails, slugs) often have a spiral shell and crawl on a belly-foot • Cephalopods (octopus, squid, cuttlefish, nautilus) have multiple tentacles attached to their “head”. Cuttlefish have an internal shell or “bone” and nautilus have a spiral, chambered shell. Bivalve means “two shells” Gastropod means “belly-foot” Cephalopod means head-foot

22. Mollusks- Class 1: Bivalves • Most bivalves are filter-feeders

23. Mollusks, Class 2: Gastropods Gastropods crawl on their bellies. They scrape up food with a tongue-like organ called a radula. Most gastropods have two small eyes at the end of tentacle-like stalks above their “heads” Slugs lack shells, but most gastropods have spiral shells with torsion. Sea snails include many species, such as whelks and conchs. snail Eyes Radula slug Sea snail

24. Mollusks, class 3: Cephalopods • Cephalopods include octopus, squid, cuttlefish and nautilus • Most cephalopods are carnivorous predators with tentacles or “arms” octopus squid cuttlefish nautilus

25. Cephalopods in Action

26. Parts of a Squid

27. Differences in cephalopods * The term tentacle is used here for all tentacle-like limbs. In fact, the smaller limbs of the squid are properly called “arms”, and only the longer ones are “tentacles”.

28. The Colossal Squid Largest Invertebrate Ever? For over 100 years, scientists had suspected that there were some really large squid lurking in the deep oceans. Jules Verne wrote a fictional account of such a creature in his 1870 novel “20000 Leagues Under the Sea” In 2003 a complete specimen of a young squid was found (shown on table above) In 2007 one weighing over 1000 lb was captured near Antarctica (upper left) Possible length of adult?

29. Convergent Evolution Mollusks and vertebrates have evolved separately for nearly a billion years, so they have no close common ancestors. Nevertheless, some features of cephalopods are remarkably similar to features found in some vertebrates. This is a case of convergent or parallel evolution. octopus eye Cat’s eye octopus beak Parrot beak 

30. Convergent Evolution cuttlefish camouflage chameleon camouflage 

31. 1. Define a mollusk • 2. List the three types of mollusk, and give an example of each. • 3. What is the largest known mollusk? • 4. What is convergent evolution? • 5. Give three examples of convergent evolution features that appear in mollusks, and state what other organism they are convergent to.

32. Annelids Phylum Annelida

33. Annelids: the Segmented Worms • Examples • Earthworms • Sandworms • Leeches

34. Geological Timescale (Arthropods) Crustaceans (Shrimp, Lobsters, Crabs etc.)  Extinct Trilobites  Extinct Sea Scorpions Annelid Ancestor (Worm) Horseshoe Crabs Chelicerates Arachnids (spiders, scorpions, mites, ticks) Sea spiders Myriapods (Millipedes & Centipedes) Uniramia Insects 543 510 439 409 363 290 245 206 144 65 2 Jurassic Ordovician Devonian Carboniferous Triassic Ternary Cambrian Permian Cretaceous Silurian Quaternary

35. Giant EarthwormThe Largest Annelid

36. That’s why some people (inaccurately) say that worms have Five hearts Facts about annelids • Annelids are called “segmented worms” because their bodies appear to be made of about a hundred similar segments stuck tightly together. • Most annelids are hermaphrodites, they have both male and female sex organs, but they must still mate with different worms. • Earthworms have no real heart, but they have five pairs of “aortic arches” that pump blood • Annelids have “setae” that extend from their body like tiny legs. Earthworms’ are hair-like and retractable, but sandworms have paddle-like setae.

38. Arthropods Phylum Arthropoda

39. Arthropods • Joint-legged invertebrates • Trilobites (extinct) • Crustaceans • Insects • Arachnids) • Centipdes & Millipedes • See phylogenetic tree (p. 745)

40. Arthropod Features • All arthropods have… • An exoskeleton (external skeleton containing a tough carbohydrate compound called chitin) • Jointed appendages (legs and/or claws) • Segmented body design • Ventral nerve cord (their main nerve goes down their belly side instead of their back side) Segmented body Tough exoskeleton ventral nerve Jointed legs

41. Most (but not all) arthropods also have these features… • Compound eyes • Eyes containing hundreds of individual lenses • Moulting • As the arthropod grows is must shed its old exoskeleton several times.

42. Arthropods, Subphylum 1: Trilobites • Trilobites were ocean-dwelling arthropods of the Palaeozoic era. • Trilobites are all extinct. They are found only as fossils Artist’s conception of trilobite Trilobite fossil

43. Arthropods Subphylum 2: Crustaceans • Most crustaceans are aquatic: • crabs*, lobsters, crayfish, barnacles and shrimp. • Two types of crustaceans are terrestrial, and are often mistaken for insects. • Sow-bug, pill-bug Sow bug pill bug *except the horseshoe crab, which is more closely related to the arachnids

44. Body Parts in a Crustacean • The body is divided into two main regions • The cephalothorax ( a fused head & thorax protected by a tough “shell” or carapace) • The abdomen (segmented tail area) • Most crustaceans are decapods (meaning 10 legs). They have four pairs of walking legs and one pair of claws (chelipeds). • In addition to their main legs, they have several other appendages • Antennae and antennules • Swimmerets • Maxilla and maxillipeds • A telson (tail-piece) and uropods (tail)

45. Internal Anatomy of a Crustacean The heart of a crustacean is on its dorsal (back) side, and its largest blood vessel runs along its back. It has a complete digestive system, with a two-part stomach, a digestive gland and an intestine. Its largest nerve runs along its ventral (belly) side, from the brain to the tail, with several nerve bundles or ganglia along it. Respiration is through gills under the carapace.

46. Arthropods Subphylum 3: Chelicerates • Chelicerates include: • Sea scorpions (extinct but huge) • Horseshoe crabs • Sea spiders • Arachnids (arachnids are the only group we will examine in detail.)

47. ArachnidsPhylum Arthropoda, Subphylum Chelicerata, Class Arachnida • Arachnids include spiders, scorpions, ticks and mites. • Most arachnids have four pairs of walking legs (“eight-legged freaks”), but may also have additional appendages… • Scorpions have a pair of chelicerae (claws) • Spiders & scorpions have pedipalps near their mouth.

48. Arachnid Facts The world’s largest spider is the Goliath “bird-eater” tarantula… over 30 cm (one foot!) long with 5 cm fangs. Eriophyid mites are among the smallest of all arthropods, measuring only 125 to 250 μm in length The most venomous spider in the world is the Brazilian wandering spider

49. Arthropods, Subphylum 4: Uniramia* • Uniramia include: • Myriapods (centipedes and millipedes) • Insects (over 750 000 species of them!) *in older classification systems, Mandibulata is sometimes used instead of Uniramia

50. Myriapods: centipedes & millipedes Centipede Millipede Ok, they don’t really have exactly 100 or exactly 1000 legs. ‘nuff said.