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Chordata
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- 2. Phylum Chordata ● Diversephylum, but much less than arthropods, or molluscs ● Most advanced of the animal phylum ● Most complex anatomy (e.g., nervous, circulatory systems etc.) ● Some of the largest animals that have ever lived 2
- 3. Phylum Chordata Membership basedon possession of five characteristics - Do not have to be present throughout entire lifetime - Only during some life stage 1. Notochord 2. Pharyngeal gill slits (pouches) 3. Endostyle or thyroid gland 4. Post-anal tail 5. Dorsal tubular nerve cord 3
- 4. Phylum Chordata 1. Notochord -Flexible rod-like structure - Enclosed by a fibrous sheath - Extends the length of the body - Provides basic support - Serves as main axis of support and for muscle attachment for undulatory, fish-like movements - First part of skeleton in embryo 4
- 5. Phylum Chordata Notochord - Inprimitive chordates, the notochord persists throughout life - Most chordates replaces it with the vertebral bone - Remnants remain as intervertebral discs 5
- 6. Phylum Chordata 2. Pharyngeal(gill) slits - Slit -like openings leading from throat to outside - First evolved as filter feeding apparatus - Still used as such in some groups - Used as gills in many aquatic forms - Many groups only have as embryos and loose as adults 6
- 7. Phylum Chordata Pharyngeal (gill)slits - Slit -like openings leading from throat to outside - First evolved as filter feeding apparatus - Still used as such in some groups - Used as gills in many aquatic forms - Many groups only have as embryos and loose as adults 7
- 8. Phylum Chordata 3. Endostyleor thyroid gland - Tissue only found in chordates - Originally part of the feeding apparatus - Secreted mucus to trap food inside the pharyngeal cavity - In most chordates becomes an endocrine gland - Helps control metabolism 8
- 9. Phylum Chordata Endostyle orthyroid gland - Tissue only found in chordates - Originally part of the feeding apparatus - Secreted mucus to trap food inside the pharyngeal cavity - In most chordates becomes an endocrine gland - Helps control metabolism 9
- 10. Phylum Chordata 4. Post-analtail - Mobility for aquatic chordates - Efficient propulsion unit - Fins added for increased efficiency - Terrestrial chordates use tail for leverage and balance 10
- 11. Phylum Chordata Post-anal tail -Mobility for aquatic chordates - Efficient propulsion unit - Fins added for increased efficiency - Terrestrial chordates use tail for leverage and balance 11
- 12. Phylum Chordata 5. Dorsaltubular nerve cord - Most inverts have the nerve cord as ventral - Paired with paired ganglia along its length - Chordates have single hollow nerve cord - Anterior enlarged into brain 12
- 13. Phylum Chordata Three majorSubphyla - Urochordata (tunicates) - tail chordates - Cephalochordata (lancelets) - head chordates - Vertebrata (vertebrates) 13
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- 15. Subphylum Urochordata Tunicates andsea squirts - 1,600 species - All marine - All depths - Adult form as suspension feeder (catch particles in water) - Many live colonially on rocks or other hard surfaces 15
- 16. Subphylum Urochordata Tunicates andsea squirts - Adults lack all chordate characters - More sponge-like - Sessile - Lack a coelom - Pump water through siphons - Tadpole larvae have all typical chordate features 16
- 17. Subphylum Urochordata Tunicates andsea squirts - Adults have tough, nonliving covering - Tunic - Filter feeders - Incurrent siphon → pharyngeal slits → atrium → excurrent siphon - Endostyle secretes mucus on pharynx - Mucus and cilia move food to mouth 17
- 18. Subphylum Urochordata Tunicates andsea squirts - Respiration - Pharynx serves all functions - Circulation - Open circulatory system - Small heart with two major vessels - Excretion - No specialized organs - Reproduction - All monoecious 18
- 19. Subphylum Cephalochordata Lancelets - 29species - Closest living relatives to vertebrates - Several characters intermediate between vertebrates and invertebrates - All chordate characters as adults - Lack internal skeleton 19
- 20. Subphylum Cephalochordata Lancelets - Burrowersand swimmers - Body laterally compressed and fish- or eel-like - Ventral surface is flattened and bears metapleural folds - Most of time spent burrowed with only head exposed 20
- 21. Subphylum Cephalochordata Lancelets - Fish-likefins with reinforcing rays - Movements - V-shaped bundles of muscles (myotomes) - Feeding and digestion - Filter feeders - Mouth surrounded by oral hood, wheel organ, and cilia - All work to draw in water - Pharynx strains particles from water - Hepatic caecum (liver) 21
- 22. Subphylum Cephalochordata Lancelets - Circulation -Closed system but no heart - Respiration - Some through pharynx - Most via diffusion across body wall - Nervous system - Hollow nerve cord - Photoreceptive cells - Excretion - Nephridia similar to annelids 22
- 23. Subphylum Cephalochordata Lancelets - Reproduction -All diecious - Larvae resemble adults - But covered in cilia 23
- 24. Subphylum Vertebrata Most complexgroup of animals Fish became first true vertebrates - Oldest known fossils of a vertebrate (560 mya) Only one invertebrate group evolved flight - Two (3*) vertebrates evolved powered flight - All other show some gliding 24
- 25. Subphylum Vertebrata Most complexgroup of animals Major characters 1. Internal jointed skeleton - Bone or cartilage - Living tissue - Cartilage first, then bone - Axial and appendicular skeleton 25
- 26. Subphylum Vertebrata Most complexgroup of animals Major characters 2. Segmented skeletal muscles - W-shaped muscle fibers - Heightened control of body movements 26
- 27. Subphylum Vertebrata Most complexgroup of animals Major characters 3. Complex skin - Multilayered - Dermis and epidermis - Contains - Sensory receptors, glands, keratin structures (hair, scales, feathers) 27
- 28. Subphylum Vertebrata Most complexgroup of animals Major characters 4. More efficient digestive system - Food moved by peristaltic contractions not cilia - Acid producing stomach - Accessory glands - Pancreas, liver 28
- 29. Subphylum Vertebrata Most complexgroup of animals Major characters 5. Efficient respiratory system tied to circulation - Pharyngeal slits for filtering became functional gills 29
- 30. Subphylum Vertebrata Most complexgroup of animals Major characters 6. Increasingly efficient circulation - Ventral heart - Closed circuit - heart chambers (2, 3, 4) - RBC’s use hemoglobin as respiratory pigment 30
- 31. Subphylum Vertebrata Most complexgroup of animals Major characters 7. Most complex nervous system - Well developed head and sensory organs - Lifestyle shift from filter feeding to predation - CNS and PNS 31
- 32. Subphylum Vertebrata Most complexgroup of animals Major characters 8. Improved efficiency of excretory organs - Paired kidneys - Dual role for metabolic wastes and osmoregulation 9. Almost all are dioecious and reproduce sexually 32
- 33. Classification of vertebrates -Jaws present or absent - Agnatha - jawless - Gnathostomata - mouth with jaws - Fins versus walking legs - Pisces - paired fins for swimming - Tetrapoda - paired limbs for terrestrial locomotion - Development - Anamniotes - offspring do not develop in a fluid-filled sac; fishes and amphibians - Amniotes - offspring do develop in a fluid-filled sac; reptiles, birds, mammals 33
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