Diversity of life ii lecture 4
- 1. AP Biology Invertebrate: Annelida Segmented worms earthworms, leeches segments increase mobility redundancy in body sections bilaterally symmetrical true coelem fan worm leech
- 2. Phylum Annelida Characteristics • Protostomia, coelomates. • Metamerism (= unspecialized segmentation).
- 3. Annelida - Systems • Integument - epidermis is one cell layer with mucous gland that secrete a moist cuticle. • Skeletal - hydrostatic (using coelom). • Muscle - longitudinal and circular muscles. • Each segments muscles are independent of the other segments. • Digestive - complete, complex, with typhlosole for absorption and chloragogen cells acting as digestive gland and excretory cells.
- 4. Annelida - Systems • Excretory - a pair of nephridia per segment. • Respiratory - through skin, some through parapodia; tubeworms have gills. • Circulatory - closed system (5 hearts), use hemoglobin as oxygen carrier. • Nervous - dorsal brain; ventral, double, solid nerve cord, with ganglia in each segment. • Endocrine - hormones secreted by nervous system. • Reproductive - • Dioecious in Polychaeta; no special organs, posterior end becomes gonads. • Monoecious in Oligochaeta and Hirudinea; Clitellium.
- 6. Class Polychaeta • Class: Class Polychaeta (mostly Marine) • Have many setae/bristles. • Highly specialised head regions. i Antennae. ii Sensory palps. iii Feeding appendages. • Paired extensions of body (parapodia). • Often tube-dwelling. • Burrow into substrate and secrete mucus materials.
- 10. Class Oligochaeta • Lack parapodia and have few setae. • Lack the distinctive head region of polychaetes and have no eyes. • Scavengers that consume soil that contains organic matter. • The ingested soil moves into a storage chamber called the crop, then to an area called the gizzard, where grinding action breaks down the soil particles. • Undigested material passes out the anus in a form called castings, which are prized as soil fertilizer.
- 12. Class Hirudinea • Most live in fresh bodies of water, but some live among moist vegetation. • Dorso-ventrally flattened. • Suckers found on both ends. • Unlike other annelids, its segments are not separated internally. • Leeches lack both setae and parapodia. • Most are predators or scavengers (detritus feeders). • Very few are parasites. • They secrete anticoagulants, hirudin, to keep blood from clotting and anesthetic that prevents the host from feeling their presence.
- 13. Class Hirudinea - Anatomy
- 14. Importance of Annelids • Earthworms eat decomposing organic material and dig tunnels in the soil aerating the soil. • They act as decomposers and as fertilizers too. • Leeches suck blood and are parasitic but medicinally this has been used in blood-letting and reconstructive surgery of severed digits and plastic surgery. • The water based annelids bio-monitor the marine environment.
- 16. AP Biology Invertebrate: Arthropoda Spiders, insects, crustaceans most successful animal phylum bilaterally symmetrical segmented specialized segments allows jointed appendages exoskeleton chitin (carbohydrate) + protein
- 17. AP Biology Arthropod groups insects 6 legs, 3 body parts crustaceans gills, 2 pairs antennae crab, lobster, barnacles, shrimp arachnids 8 legs, 2 body parts spiders, ticks, scorpions
- 18. Phylum Arthropoda • includes spiders, scorpions, horseshoe crabs, centipedes, crustaceans, insects. • The largest and most diverse animal phylum.
- 19. Phylum Arthropoda • Almost 2/3 of all species that have been described are arthropods. • There may be as many as 30,000,000 species of insects alone. • Abundant in all habitats, but dominate in terrestrial habitats. • Most arthropods are small, but a few may be as large as 3.6 m.
- 20. Phylum Arthropoda • Economical, environmental and health importance: • Pollination. • Food source. • Pests. • Disease vectors.
- 21. Phylum Arthropoda Taxonomy of Arthropods • Arthropods divided into three subphyla - based on appendages: 1. Chelicerata: • first appendages are for feeding – (chelicerae -fangs of spiders, feeding appendages of horseshoe crabs). 2. Mandibulata: Crustacea and Uniramia (Tracheata): • first appendages are antennae, first feeding appendages are called mandibles. 3. Trilobita: • Extinct.
- 22. 22 Phylum Arthropoda - Alternate Classification 1. Subphylum Trilobita • extinct trilobites 2. Subphylum Chelicerata • horseshoe crabs, spiders, ticks, mites, and some extinct groups 3. Subphylum Myriapoda • centipedes, millipedes 4. Subphylum Crustacea • crabs, lobsters, shrimps, barnacles 5. Subphylum Hexapoda • Insects
- 24. Mandibulates: Crustaceans and Uniramians • Mandibulates are divided into two major groups - Crustaceans and Uniramians (Tracheata) - based on appendages. • Crustaceans have biramous (branched) appendages. • Uniramians (insects, millipedes, centipedes) have uniramous (unbranched) appendages.
- 25. Key Innovations of arthropods • Jointed appendages - Arthropod (jointed feet). • Jointed appendages are specialised for different functions: legs, mouthparts, antennae. • Joints in appendages make them highly functional for walking, and grasping. • Antennae are sensory - sounds and chemicals. • Mouth parts specialised for different food sources. • Exoskeleton, segmental body with specialisation of body regions.
- 26. Arthropods – Breathing mechanisms • Terrestrial Uniramians and some Chelicerates have trachea. • Trachea are branched tubules that allow air to diffuse into the body • Smaller tracheoles bring air to individual cells. • Air entry controlled through external spiracles and closing of spiracles conserves water. • Flow is mostly passive - muscular movements can increase flow. • Limits body size because all cells must be able receive oxygen.
- 27. Arthropod – Skeletal Support System • Rigid exoskeleton, made of chitin and protein helps to protect organism against predators. • Reduces desiccation (water loss) - allows life in dry environments. • Skeleton functions as attachment for muscles. • Exoskeleton limits arthropods maximum size although chitin is tough, it is brittle and cannot support great weight without increasing its thickness greatly. • Exoskeleton must be shed in order for increase in size.
- 28. Arthropod - Moulting • Growth requires periodic moulting - liability. • New exoskeleton grows beneath old one separated by a fluid that dissolves components of old skeleton. • Old skeleton cracks open and is shed. • New skeleton is soft and must be expanded to full size. • Hardens with exposure to air or water.
- 29. Arthropods - Segmentation • Segmental body plan clear in all forms. • Segments fused to form specialised body regions. • Insect: head, thorax, abdomen. • Crustacean: cephalothorax, abdomen.
- 30. Arthropods - Eyes • Ocelli are simple eyes with single lenses. • Sometimes occur together with compound eyes. • Function in distinguishing light and dark. • Compound eyes: composed of many ommatidia. • Each ommatidium receives its own image. • it is connected to a nerve cell - entire image is integrated in the brain.
- 31. Arthropod – Digestive system • Gut is tubular and extends from mouth to anus - with specialization: - crop, stomach (midgut), hindgut, intestine, rectum.
- 32. Arthropod Circulatory system • Circulatory system is open. • Heart extends through thorax and abdomen. • Contraction sends blood forward and relaxation draws blood from tissues. • One-way valves in heart allows blood to flow forward only. • Blood from anterior end flows through tissues to posterior end.
- 33. Arthropods – Respiratory system • Crustaceans have feathery gills under carapace. • Chelicerates have book gills and book lungs - series of plates with thin respiratory epithelium.
- 34. An efficient system that conserves water - a good adaptation for terrestrial life Arthropods - Excretion • Several forms of excretory systems. • Terrestrial Uniramians have Malpighian tubules. • Slender tubular projections off the digestive tract at the junction of the midgut and hindgut. • Water and solutes pass through walls of tubules, nitrogenous wastes are precipitated as uric acid. • Fluid with waste is emptied into hindgut and eliminated. • Most water and valuable solutes reabsorbed by hindgut.
- 35. Arthropods – Nervous System • Double chain of ganglia runs along ventral surface. • Three fused pairs of dorsal ganglia form the brain. • Ventral ganglia control local activity of body regions. • Many activities continue with brain removed. • Some activities begin spontaneously when head is removed.
- 36. Subphylum Chelicerata Three Classes of Chelicerates • Class Arachnida - spiders, scorpions, ticks • Class Merostomata - horseshoe crabs • Class Pycnogonida - sea spiders
- 37. Class Arachnida • Spiders, daddy longlegs, scorpions, mites & ticks. • All have a pair of chelicerae, pair of pedipalps, four pairs of legs. • Chelicerae are first appendages, fangs with poison glands. • Pedipalps are next, similar to legs - rarely used for locomotion often used for catching and handling prey. • may also chew with basal portion. • may function as copulatory organs or sensory organs. • Scorpion pincers are pedipalps.
- 38. Class Arachnida • Most are carnivorous, some mites are herbivorous. • Most ingest only liquified foods, digestion begins externally. • Most are terrestrial, direct transfer of sperm for reproduction. • Respire with trachea, book lungs or both.
- 39. Class Merostomata Horseshoe Crabs e.g.: Limulus sp, common on North Atlantic coasts. • Ancient group - Limulus fossils date to 220 million years old. • Live in deep water, migrate to shallow coastal waters to mate. • Feed at night on molluscs and annelids. • Shell-like carapace over cephalothorax protects most body parts. • Possess four pairs of walking legs, chelicerae and pedipalps. • Respire via five pairs of book gills.
- 40. Class Pycnogonida Sea Spiders. • Common in marine habitats, especially in cool waters. • Rarely observed because of small size. • Not closely related to spiders. • Adults are parasites or predators on other animals. • Have sucking proboscis with terminal mouth. • Body consists mostly of cephalothorax, no well-defined head. • Possess four to six pairs of legs. • Males exhibit parental care of young, carry eggs on legs.
- 41. Subphylum Mandibulata Class Crustacea – Crustaceans. • Includes shrimp, crabs, crawfish, lobsters, pillbugs, copepods, brine shrimp and barnacles. • Have biramous (two branch) appendages. • Have two pairs of antennae. • 3 pairs of feeding appendages. • Larger forms have feathery gills near base of legs.
- 42. Class Crustacea • Have legs on thorax and abdomen like millipedes and centipedes. • Unlike insects crustaceans have two pairs of antennae. • Many have compound eyes. • Have tactile (touch sensitive) hairs over whole body. • Excretion of nitrogen wastes occurs mostly across surface of cuticle. • Variety of sexual styles and care of young.
- 43. Crustacean Diversity • Decapod ("ten-footed") Crustaceans - • includes lobsters, shrimp, crabs, crawfish. • Exoskeleton reinforced with calcium carbonate. • Anterior segments fused into cephalothorax, covered by carapace. • Crushing pincers common, used to obtain food and in defence. • Swimmerets used in reproduction and locomotion. • Snapping of telson and uropods causes forceful, rapid movement to the rear.
- 44. Crustacean Diversity • Terrestrial forms - pillbugs, sowbugs, isopods. • Amphipods are both terrestrial and aquatic. Planktonic crustaceans: • Subclass: Copepods (Copepoda). • Subclass: Water fleas (Cladocera). • Subclass: Ostracods (Ostracoda). • Fairy shrimp and brine shrimp (Anostracoda).
- 45. Subphylum Uniramia Uniramia (or Tracheata) - has three classes: • Class Chilopoda – centipedes. • Class Diplopoda – millipedes. • Class Insecta – insects. • Well adapted to terrestrial life. • Respire with trachea. • Malpighian tubules for excretion. • Waxy cuticle on exoskeleton.
- 46. Classes Chilopoda and Diplopoda Centipedes and Millipedes - both have head tagmata followed by numerous repeating segments - each with paired appendages. • Centipedes (hundred legs) - have one pair of legs per segment. • Millipedes (thousand legs) - have two pairs of legs per segment.
- 47. Class Chilopoda and Diplopoda • Centipedes - carnivorous, most eat insects. • Appendages of first body segment are poisonous fangs. • Millipedes - most are herbivorous. • Can roll bodies into a flat coil. • May secrete defensive fluids and cyanide gas. • Reproduction similar in both groups. • Sexes separate, fertilization is internal, copulate to transfer sperm, all species lay eggs. • Juveniles are similar to adults in appearance.
- 48. Class Insecta Class Insecta – Insects. • Largest group of organisms on earth - with great diversity. • Especially numerous in the tropics.
- 51. Class Insecta • Most are terrestrial but many are aquatic in freshwater. • Have three body segments: Head, thorax, abdomen. • Have three pairs of legs, all attached to thorax. • Have one pair of antennae. • May have one or two pairs of wings. • Sexes separate with internal fertilisation. • Wings arise as sack-like outgrowths. • Wings are solid except for veins.
- 52. Class Insecta • Digestive tract is tubular and slightly coiled digestion occurs within stomach or midgut. • Excretion by Malpighian tubules. • Respiration via trachea that extend throughout body. • Spiracles can be closed by muscles to retard water loss.
- 53. Class Insecta • Possess wide variety of sensory systems - in addition to eyes. • Sensory hairs located all over bodies especially on legs and antennae. • Sounds detected by tympanum. • Sensory hairs may also detect sound waves. • Produce sounds which may be inaudible to humans. • Chemicals (pheromones) are also used to communicate.
- 54. Class Insecta - Development • Most insects hatch from laid eggs - rarely develop within mother. • After hatching young insects undergo development through a series of instars. • Often the larva is very different from the adult and undergoes metamorphosis to become adult. • Development is either through simple metamorphosis or incomplete metamorphosis.
- 55. Class Insecta Incomplete metamorphosis (Hemimetabolous development).
- 56. Class Insecta Complete metamorphosis (Holometabolous development)