Invertebrates

1. Invertebrates Packet #38

2. Introduction I

3. Introduction II

4. Invertebrates- Animals Without Backbones • Ninety five percent of all known animals species are invertebrates. • Invertebrates have a worldwide distribution ranging from deep sea hydrothermal vents to the polar deserts of Antartica.

5. Major Clades of Coelimates Protosomes Lophotrochozoa Phylum Porifera (The Sponges)

6. Introduction I • Phylum Porifera (pore bearer) sponges are sessile with porous bodies and choanocytes. • Sessile animals • They have no nerve or muscle tissue but individual cells can react to environmental changes. • There are 9000 species & approximately only 100 live in freshwater, the rest are marine. • Characterized by flagellate collar cells—chaoanocytes • Sponges are suspension feeders and they evolved from colonial choanoflagellate. • Sponges range in size from a few mm to a few meters. • They produce a variety of antibiotics and other defensive compounds.

7. Introduction III Sponges are hermaphrodites and almost all exhibit sequential hermophroditism. Gametes develop from both choanocytes and amoebocytes. Eggs remain in the mesophyl while sperms are carried out of the sponge by water current. Cross fertilization occurs when sperm are drawn into others sponges. Fertilization occurs in the mesophyl forming zygotes that develop into flagella larvae. Once settled on a suitable substrate the larvae develop into a sessile sponge

8. Introduction II • The sponge body is a sac with tiny openings through which water can flow • Central cavity • Sponogocoel • Water enters here • Open end • Osculum • Water exits here • The cells of the sponge are “loosely” associated • They do not form true tissue

9. Ingestion of Materials • Water is drawn through the pores into a central cavity called spongocoel. • Water flows out through a larger opening called the osculum. • Sponges collect food particles with specialized food trapping cells called choanocytes (i.e. collar cells) which line the interior of the spongocoel. • Choanocytes use their flagella to create a current and then use their collars to trap the particles which are ingested by phagocytosis.

10. Major Clades of Coelimates Protosomes Lophotrochozoa Phylum Cnidaria

11. Introduction I • There are four classes of this phylum • Hydrozoa • Cubozoa • Scyphozoa • Anthozoa • Characteristics • Radial symmetry • Two tissue layers • Diploblasic • Contain cnidocytes • Cells that contain organelles with stinging abilities called nematocysts • Gastrovascular cavity serves as both the mouth and anus. • The nerve cells are irregular, non-directional (nerve nets) • Connect sensory cells with contractile and gland cells

12. Introduction II • “True” tissue • There are over 10,000 species • Occur in two forms • Polyps • Sessile • Medusa • Floats • Often canivorous

13. Classes I • Class Hydrozoa • Hydras, hydroids, and Portuguese man-of-war • Polyps • May be solitary or colonial

14. Classes II • Class Scyphozoa • Jelly fish; Sea nettles • Generally medusa • Class Cubozoa • Sea wasps; box jellies • Class Anthozoa • Polyps • May be solitary or colonial • Sea anemones • Most corals & sea fans

15. Classes III

16. Major Clades of Coelimates Protosomes Lophotrochozoa Phylum Ctenophora (The Comb Jellies)

17. Introduction Fragile Luminescent marine predators Display bi-radial symmetry Contain eight rows that resemble combs Diploblastic Have tentacles with adhesive glue cells.

18. ProtostomeCoelomates

19. Introduction Spiral cleavage Determinate cleavage Mouth develops from the blastopore

20. Coelomate“Evolutionary” Adaptations • Allowed the formation of • The tube-within-a-tube body plan • The hydrostatic skeleton • Provides space for the organs and gonads to develop • Helps transport materials • Protects internal organs

21. The Protostomes LophotrochozoaPhylum Nemertea (Ribbon Worms)

22. Introduction • Characterized by proboscis • Muscular tube used in capturing food • Muscular tube used in defense • Coelom is reduced • Consists of the rhynchocoel • Space surrounding the proboscis • Have a tube-within-a-tube body plan • Have complete digestive tract with mouth and anus • Have a circulatory system

23. Protosomes Phylum Platyhelminthes (The Flatworms)

24. Introduction I • Commonly referred to as the flatworms because their bodies are thin between the dorsal and ventral surfaces • Some are free living or parasites • Live in marine, freshwater and/or damp terrestrial habitats • Divided into four classes (No details this year ) • Turbellaria • Monogenea • Trematoda • Cestiodea (Tapeworms)

25. Introduction II • Acoelomate animals • Bilateral symmetry • Cephalization • Connection of the head • Concentration of nervous tissue at the front end of the animal • Have a ladder-type nervous system • Sense organs and a simple brain • Consists of two nerve cords that extend the length of the body • Many are hermaphrodites • Animal develops both sperm and eggs • Have protonephridia • Organs that function in osmoregulation and disposal of metabolic wastes

26. Protosomes Phylum Mollusca (The Mollusks)

27. Mollusks

28. Introduction I • Soft-bodied animals usually covered by a shell • Have a ventral foot for locomotion • Have a mantle that covers the visceral mass • Visceral mass • Concentration of body organs • Open circulatory system • Exception Cephalopods (squids, octopods) • Have paired excretory tubules and metanephridia • Have rasplikeradula • Functions as a scraper in feeding • Marine mollusks are free-swimming, ciliated trochopore larva

29. Introduction II • Class Polyoplacophora • Sluggish marine chitons • Class Gastropoda • Largest group of mollusks • Snails; slugs • Bodies undergo “torsion” • Visceral mass rotates up to 180º causing the animal’s mantle and head to end up above it’s head • Class Bivalvia • Aquatic clams; scallops; oysters • 2 part shell, hinged dorsally, encloses the bodies of these suspension feeders • Class Cephalopoda • Squids; Octopods • Active and predatory swimmers • Tentacles surround mouth

30. Major Classes of Phylum Mollusca

31. Protosomes Phylum Annelida (The Segmented Worms)

32. Introduction I • 15,000 species that include • Many aquatic worms • Others live in freshwater or terrestrial habitats • Earthworms • Leeches • Conspicuous long bodies with segmentation internally and externally • Large compartmentalized coelom serves as a hydrostatic skeleton

33. Classes Annelida • Class Polychaeta • Marine worms • Have appendages called parapodia • Used for locomotion and gas exchange • Bear setae • Class Oligochaeta • Earthworms • Named for their sparse setae which are bristles composed of chitin • Important to farming • Castings, aeration, soil texture and tilling • Class Hirudinea • Leeches • Characterized by the absence of sate and appendages • Parasitic leeches are equipped with suckers at anterior and posterior ends.

34. Evolutionary Connection • Adaptations • Development of coelom • Provides a hydrostatic skeleton • Body space for storage and complex organ development • Protection • Cushion for internal structures • Segmentation • Allows for a high degree of specialization of body regions

35. Protosomes Lophotrochozoa Phylum Nematoda (The Roundworms)

36. Introduction I • Non-segmented psuedocoelomates covered with a tough cuticle that prevents desiccation • Over 90,000 species • Bilateral symmetry • Triploblastic • Complete digestive system • Zygotes are able to survive harsh conditions • Parasitic Nematodes • Ascaris, hookworms, trichina worms, pinworms • Agricultural pests • Attack plant roots.

37. Protosomes Lophotrochozoa Phylum Arthropoda (Jointed Feet)

38. Introduction I • Segmented animals • Have paired, jointed appendages • Specialized for walking, feeding, sensory reception, sex and defense • Exoskeleton of protein and chitin • Thick spots are armor • Molting is necessary for arthropods to grow • Evolutionary Connection • Moved out of water following plants and the fungi

39. Introduction II • Open circulatory system with a dorsal hear that pumps hemolymph. • Evolution Connection • System evolved convergently in the mollusks and arthropods • Aquatic forms have gills • Terrestrial forms have either tracheae or book lungs

40. Introduction III • Trilobites • Extinct maring arthropods covered by a hard segmented shell • No connection to the theory of evolution right now*RB

41. Subphylum Myriapoda • Have unbranced appendages • Single pair of antennae • Class Chilopoda • Centipedes • Class Diplopoda • Millipedes

42. Subphylum Chelicerata • Body consists of a cephalothorax and abdomen • No antennae or mandibles • There are six pairs of jointed appendages • Appendages are for manipulation of food, locomotion, defense or copulation. • Four pairs serve as legs • First pair • Chelicerae • 2nd Pair • Pedipalps

43. Subphylum Crustacea • Lobsters, crabs, shrimp, pillbugs and barnacles • Body consists of a cephalothorax and abdomen • Typically have five pairs of walking legs • Have two pairs of antennae • Sense taste and touch • Third appendages are mandibles • Used for chewing • Two pairs of maxillae, posterior to the mandibles • Manipulate and hold food

44. Subphylum Hexapoda • Includes class Insecta • Considered to be an articulated, tracheated hexapod • Body consist of head, thoarax and abdomen • Have tracheae for gas exchange • Have Malpighian tubules for excretion • Have unbranched appendages • Single pair of antennae

45. Hexapods II • Live in almost every terrestrial habitat and in freshwater • Rarely found in a marine environment • Success is associated with the ability to fly • Can escape predators • Find food and mates • Disperse to new habitats faster • May also help, from an “evolutionary” perspective, explain the diversity of insects and angiosperms

46. Hexapods III • Body is divided into three parts • Head • Thorax • Abdomen • Antennae are present • Mouth parts are modified for chewing, sucking and lapping • Have three pairs of legs • Internal anatomy has complex organ systems. • Waste removed from hemolymph via malphigian tubules • Tracheal system lined with chitin carries O2 • Nervous system consists of ventral nerve cords with several segmental ganglia • Metamorphosis is central to insect development • Most insects only mate once • Females lay eggs on a food source for next generation

47. Insect Diversity

48. Insect Diversity II

49. “Evolution” Connection • Wings • First evolved as extensions of the cuticle that helped the insect absorb heat and were later modified for flight • Not true appendages • May have served as gills in aquatic insects • Wings functioned for swimming • Allowed animals to glide from the vegetation to the ground

50. Deuterostomia (Second Mouth)the Deuterostomes