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2. 2 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Sylvia S. Mader Immagini e concetti della biologia

3. 3 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 A11 - Animal evolution

4. 4 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Kingdom Animalia Animals are heterotrophic for ingestion, must acquire nutrients form an external source. The kingdom Animalia includes all multicellular eukaryotic organisms.

5. 5 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Kingdom Animalia Animals normally reproduce sexually and undergo developmental stages that produce specialized tissues and organs. Frog developmental stage from zygote to tadpole

6. 6 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Animals have a Protistan ancestor The “Colonial flagellate hypothesis” states that animals evolved from flagellated protists that lived in colonies.

7. 7 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Animals derived characters Animals have a bilateral or radial symmetry. Bilateral: only one longitudinal plane cut the body in two identical pieces. Radial: Several longitudinal planes produce roughly identical pieces.

8. 8 Evolutionary tree Animals traditional evolutionary tree is based on the seven key traits of the structure. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

9. 9 The body cavity The body cavity is a fluid-filled space, called coelom, located between the epidermis and the gut cavity, where internal organs develop. Coelomate Animals: most bilateral animals Pseudocoelomates: have a “false body cavity” Acoelomates: have no body cavity

10. 10 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 The body cavity Coelomates divides into protostomes or deuterostomes, based on the embryonic development.

11. 11 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Coelomate animals A blastopore is an opening into the digestive tract during the embryonic stages. The difference between protostomes and deuterostomes depends on the position the mouth develops in relation to the blastopore. Blastopore mouth anus mouth

12. 12 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Coelomate animals Coelom Some advantages of coelom: independent movement of the body space for complex organs storage area for eggs and sperm protection from mechanical shocks support

13. 13 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vertebrates and invertebrates Animals are further divided into: INVERTEBRATES without an endoskeleton of cartilage or bone (i.e. sponges and mollusks). VERTEBRATES those that have an endoskeleton (i.e. fish and mammals).

14. 14 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Porifera The simplest animals are the sponges, multicellular filter feeders that lack organized tissues.

15. 15 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Cnidaria Cnidarians are mostly sessile marine animals with radial symmetry and a sac body plan. Tissue level of organization. Two body stages: polyp (sessile) and medusa (free moving).

16. 16 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Platyhelminthes In flatworms appears bilateral symmetry. They are parasites of humans and other animals. Three germ layers Acoelomates Ladder like nervous system Incomplete digestive tract

17. 17 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Nematoda Roundworms are non segmented, show a complete digestive tract and have a pseudocoelom. Some nematodes as Ascaris are endoparasites of humans. Ascaris

18. 18 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Annelida In annelids, rings encircle the body and septa divide the coelom. The phylum includes Polychaetes, earthworms and leeches. Mouth Brain Coelom

19. 19 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Mollusca Mollusk have a three parts body plan: mantle, visceral mass and foot. The mantle can secrete a shell. Mollusks are divided into: 1.Gastropods 2.Cephalopods 3.Bivalves Mantle Visceral mass Foot

20. 20 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Mollusca Gastropods (stomach-foot): the foot is flattened.

21. 21 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Mollusca Cephalopods (head-foot): the foot is evolved into tentacles.

22. 22 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Mollusca Bivalves: the foot projects from the shell.

23. 23 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Arthropoda Includes the largest number of species in the animal kingdom. Derived characters: external skeleton, segmented body, jointed appendages, well developed nervous system, metamorphosis. The body often divided into distinct regions called head, thorax and abdomen.

24. 24 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Arthropoda CRUSTACEAN are mostly marine arthropods with a hard exoskeleton. Have head and five pairs of walking legs.

25. 25 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Arthropoda CENTIPEDES and MILLIPEDES have multiple appendages and move efficiently on land.

26. 26 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Arthropoda ARACHNIDS as spiders and scorpions have four pairs of walking legs attached to the cephalothorax.

27. 27 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Arthropoda INSECTS: mostly terrestrial, live in every environment on Earth and are among the most highly adapted of all animal species. Their body is divided into head, thorax and abdomen with three pairs of legs attached to the abdomen.

28. 28 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Echinodermata Echinoderms are mostly marine animals with no head, brain or segmentation. adults: radial symmetry larvae: bilateral symmetry

29. 29 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Echinodermata In echinoderms a water vascular system provides locomotion and help carry out respiratory, excretory and circulatory functions.

30. 30 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Chordata All members of the chordates have bilateral symmetry as well as body cavity, head, digestive system and body segmentation. Chordates are both VERTEBRATES and INVERTEBRATES

31. 31 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Chordata During the life cycle chordates have the following derived characters: Notochord (a flexible rod that provides internal support) Nerve chord (or spinal chord) Pharyngeal pouches Postanal tail (after embryonic development)

32. 32 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Invertebrates: Chordata Invertebrate chordates have a notochord as adults. The four chordate features are present in Tunicates larval stage and in adult Lancelets. Tunicate AscidiaLancelet Anfiosso

33. 33 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vertebrates Evolutionary tree is based on five characters.

34. 34 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vertebrates All vertebrates have: Jointed endoskeleton Paired appendages Well developed coelom and viscera Cephalization A closed circulatory system Efficient respiratory and excretory systems

35. 35 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vertebrates: Agnatha Few species belong to the group of jawless fish and some of them are parasites of bigger fish (i.e. lamprey).

36. 36 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vertebrates: Chondrichthyes Those fish have cartilaginous endoskeleton. The class includes the sharks and rays. Jaws allow fish to be predaceous.

37. 37 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vertebrates: Osteichthyes Most of the familiar fish living today are bony fish. Osteichthyes is divided into: Ray-finned fish (Actinopterygii) with swim bladder control its buoyancy; Lobe-finned fish (Sarcopterygii).

38. 38 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vertebrates: Amphibia Amphibians were the first tetrapods that could move on land. Have jointed limbs, eyelids, ears, a voice-producing larynx. Lungs, together with cutaneous respiration, help the adults live on land.

39. 39 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vertebrates: Reptilia Reptiles have an amniotic egg, which contains extra- embryonic membranes, and can reproduce on land.

40. 40 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vertebrates: Aves Birds have many structural adaptations for flight. Birds are homeothermic (maintain body temperature) and lay a hard-shelled amniotic egg.

41. 41 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vertebrates: Mammalia Mammals nourish their young with milk produced by mammary glands. The presence of fur helps maintain a constant body temperature in the homeothermic mammals.

42. 42 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vertebrates: Mammalia Mammals are: Monotremes: lay hard-shelled amniotic eggs Marsupials: have a pouch in which the newborn matures Placentals: retain their offsprings inside an uterus until birth Killer whale (placental) Koala (marsupial) Duckbill platypus (monotreme)