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Invertebrates (cont.)

Invertebrates (cont.).                          Flatworms. Live in marine, freshwater, and damp terrestrial habitats Acoelomates (lack body cavity) No specialized organ for gas exchange or circulation   Most have gastrovascular cavity with only one opening to the outside.

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Invertebrates (cont.)

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  1. Invertebrates(cont.)

  2.                          Flatworms • Live in marine, freshwater, and damp terrestrial habitats • Acoelomates (lack body cavity) • No specialized organ for gas exchange or circulation   • Most have gastrovascular cavity with only one opening to the outside

  3. Turbellaria (mostly free-living flatworms) Monogenea (monogeneans) Trematoda (trematodes) Cestoda (tapeworms)                          Flatworm Classes

  4.                         Turbellarians • Members of the genus Dugesia (commonly called Planarians) • Free-living •  Moving using cilia on their ventral epidermis • Some move by using muscles to swim through water • Hermaphrodites: reproduce asexually through regeneration or sexually through cross-fertilizing

  5.             Anatomy of Turbellarian

  6.                     Monogeneans • Marine and freshwater parasites •  Mostly infect external surfaces of fish • Ciliated larva initiated infection on host

  7.                     Trematodes • Parasites (usually vertebrates) •  Many require intermediate hosts • Schistosoma (blood flukes) live in snails (intermediate host) before infecting humans • Release molecules that manipulate the hosts' immune systems into tolerating the parasite's existence

  8. Cestoidea (Tapeworms) • Parasitic (live mostly invertebrates • Absorb nutrients released by digestion in the host's intestine (absorption occurs across it's body surface) • Anterior end (scolex) armed with hooks that lock the worm to the intestinal lining of host •  Humans acquire tapeworms by eating under cooked meat with cysts 

  9. Rotifers (phylum Rotifera) • Tiny animals, inhabit fresh water, the ocean and damp soil • Have alimentary canals  •  Parthenogenesis – Type of reproduction • Some species consist only of females, that only reproduce other females • Other species produce males that cannot feed themselves and only live long enough to produce sperm to fertilize eggs

  10. LOPHOPHORATES COMPRISED OF 3 PHYLA ECTOPROCTS PHORONIDS BRACHIOPODS - All contain a “Lophophore”, a horseshoe shaped or circular crown of ciliated tentacles around the mouth

  11. ECTOPROCTS Lophophore • Resemble plants • Most live in the ocean • Are important reef builders • In most species, the colony is encased in a hard exoskeleton with pores Ectoprocts, such as this sea mat (Membranipora membranacea), are colonial lophophorates. (a)

  12. PHORONIDS • Tube dwelling marine worms • Size ranges from 1 mm to 50 cm • Some live buried in the sand within tubes made of chitin Lophophore (b) In phoronids such as Phoronis hippocrepia, the lophophore and mouth are at one end of an elongated trunk.

  13. BRACHIOPODS • - All are marine • Superficially resemble clams and other hinge-shelled molluscs • The two halves of the brachiopod shells are dorsal and ventral rather than lateral as in clams Lophophore Brachiopods have a hinged shell. The two parts of the shell are dorsal and ventral. (c)

  14. NEMERTEANS Phylum Nemertea

  15. NEMERTEANS • - Commonly called proboscis worms or ribbon worms • Is an Acoelomate • Most species are marine • Have an alimentary canal • Have a closed circulatory system, but no heart

  16. MOLLUSCS Phylum Mollusca • Most are marine but some are fresh water • Some snails and slugs live on land • Are soft-bodied but most are protected by a hard calcium carbonate shell • Molluscs body parts: Muscular foot • Visceral mass • Mantle

  17. CHITONS - Polyplacophora • Oval shaped body • Eight dorsal plates • Marine animals which cling to rocks along shore

  18. GASTROPODS - Gastropoda • Three fourths of all molluscs are gastropods • All undergo “Torsion”, which rotates its visceral mass 180 degrees • Most have a single spiraled shell • Many have a distinct head with eyes at the tips of tentacles (a) A land snail A sea slug. Nudibranchs, or sea slugs, lost their shell during their evolution. (b) Figure 33.18a, b

  19. BIVALVES - Bivalvia • Have shell divided into 2 halves that are hinged • Have powerful adductor muscles to close shell • Have no head or radula • Trap food particles in their gills

  20. CEPHALOPODS - Cephalopoda • Active predators • Use tentacles to grasp prey • Beak-like jaws inject poison • Only molluscs with closed circulatory system • Well developed sense organs and complex brains • Shells may or may not be present

  21. OCTOPUS, SQUID, AND CHAMBERED NAUTILUS (c) Chambered nautiluses are the only living cephalopods with an external shell. (a) Octopuses are considered among the most intelligent invertebrates. (b) Squids are speedy carnivores with beaklike jaws and well-developed eyes.

  22. Annelids – Segmented Worms Means “little rings” Environment Aquatic – Freshwater or Oceanic Terrestrial – Damp soil or moist environment Size – 1mm to 3m

  23. Characteristics - Annelids Characteristics Reduced head No parapodia Chaetae present – sparse or bristles mode of chitin (setae) Earthworms Digestion Eat through soil Acquire nutrients from soil Soil passed through digestion track or alimentary canal Undigested material excreted through anus Digestion till and improve texture of earth Sexual Reproduction Hermaphrodites – Male and Female Cross fertilization or Asexual Fragmentation Circulation - Closed Circulatory System Contain dorsal and ventral vessels which are connected by segmented pairs of vessels The dorsal and the segmented vessels around the esophagus are muscular and pump the blood  Gas Exchange Tiny blood vessels on the skin function as respiratory organ

  24. Oligochaeta – Earthworms & Relatives

  25. Polychaetes Characteristics Each segment has a pair of paddle like or ridge like structure called parapodia (almost feet) Increased locomotion Parapodium has several chaetae which are more numerous than Oligochaetes Parapoduim are richly supplied with blood vessels and double as gills

  26. Leeches Enviroments Aquatic – Marine and Freshwater Terrestrial – Moist vegetation & Damp environments Characteristics Length – 1 to 30 cm Predators Feed on invertebrates’ and animals’ blood Use blade like jaws or enzymes that makes holes in skin Secrete anesthetics to prey To thin blood of animals or invertebrates Leeches use anticoagulation (Hirudin)

  27. Nematodes (Roundworms) Characteristics Nonsegmented with cylindrical bodies Pseudocoelomates – liquid filled cavity where nutrients transported via pseudocoelom, this fluid acts as a meas to transport nutrients and waste Covered in a tough cuticle – shed and secrete a larger cuticle Alimentary canal and a lack of circulatory system Environments Terrestrial – Soil Aquatic – Decomposing matter on bottom of lakes and oceans Play a key role in decomposition and nutrient cycle These organisms can live in animals and humans

  28. Arthropods Characteristics Segmented coelomates Exoskeleton (Skeleton on the outside) & jointed appendages Resulted in success and diversity Exoskeleton made of layers of protein and polysaccharide chitin which varies in hardness or toughness Function : protection and anchorage for muscle (movement to land) Impermeability to water which prevents dessiction When undergoing ecdysis (molting) of exoskeleton, arthropods are very venerable because of the huge energy cost of ecdysis and their lack of exoskeleton Open Circulatory system The fluid hemolymph, blood only not in a closed system, is pumped by heart through arteries and spaces (sinuses) surrounding organs and tissues. Then it reenters the heart through pores that are usually equipped with valves Sinuses called hemocoel which are not part of coelom

  29. Anthropods Some organs specialized for gas exchange Organs allowed diffusion of respiratory gases in spite of exoskeleton Aquatic species have gills with more surface area for gas exchange than terrestrial species who have internal gas exchange Subphylum Cheliceriforms – Sea spiders, Horseshoe crabs, Scorpions, Ticks, Mites, and Spiders Myriapods – Centipedes and Millipedes Hexapods – Insects with six legs, with or without wings Crustaceans – Crabs, Lobsters, Shrimp, and Barnacles Trilobites : pronounced segmentation with very little variation With evolution the number of segments decreased and the specialization of appendages increased enabling: walking, feeding, sensory reception, copulation, and defense

  30. Major lineages In the Cheliceriforms only pyconogonidas (Sea spiders & Horseshoes Crabs) and arachnids (Spiders, Scorpions, Ticks, Mites) survive; the eurypterids and marine cheliceriforms are extinct Characteristics - Cheliceriforms Anterior cephalothorax Posterior abdomen No antennae Simple eyes (single lens) Body with one or more main parts with six pair of appentages usually Chelicerae - mouh parts Pedipalps - appendages for sensing or feeling Four pair walking legs

  31. Example – Spiders Contain poison glands which help digest or turn material into liquid. Book Lungs – Staked plate contained in internal chambers with extensive surface area and exchange O2 with CO2 between hemolymph and air Catch insects by constructing webs with silk made by spinnets Patterns and style of the web is always correct (integrated) Characteristics - Myriapods All terrestrial – Earliest animals on land Head contains pair of antennae and three pairs of appendages (mouth parts, mandibles) Eat decaying leaves and other plant matter Millipedes Diplopod class Large number of legs (less than 1000) Each trunk segment is made of 2 fused segments and has two pairs of legs Centipedes Carnivores Each segment of trunk has one pair of legs Poison claws on foremost trunk paralyzes prey

  32. Insects •Subphylum Hexapoda, insects and relatives, have more species than all other forms of life combined •They live in almost every terrestrial habitat and in fresh water •The internal anatomy of an insect includes several complex organ systems

  33. Anatomy of a grasshopper

  34. Metamorphosis •Many insects undergo metamorphosis during their development •In incomplete metamorphosis, the young, called nymphs, resemble adults but are smaller and go through a series of molts until they reach full size •Many insects undergo metamorphosis during their development •In incomplete metamorphosis, the young, called nymphs, resemble adults but are smaller and go through a series of molts until they reach full size

  35. Metamorphosis of a butterfly

  36. Crustaceans •While arachnids and insects thrive on land, crustaceans, for the most part, have remained in marine and freshwater environments •Crustaceans, subphylum Crustacea, typically have branched appendages that are extensively specialized for feeding and locomotion •Decapods are all relatively large crustaceans and include lobsters, crabs, crayfish, and shrimp

  37. •Planktonic crustaceans include many species of copepods, which are among the most numerous of all animals

  38. •Barnacles are a group of mostly sessile crustaceans •They have a cuticle that is hardened into a shell

  39. •Chordates and echinoderms share characteristics of deuterostomes:–Radial cleavage–Development of the coelom from the archenteron–Formation of the mouth at the end of the embryo opposite the blastopore Echinoderms and Chordates 

  40. Echinoderms •Sea stars and most other echinoderms are slow-moving or sessile marine animals •A thin, bumpy or spiny skin covers an endoskeleton of hard calcareous plates •Unique to echinoderms is a water vascular system, a network of hydraulic canals branching into tube feet that function in locomotion, feeding, and gas exchange

  41. Classes •Living echinoderms are divided into six classes: –Asteroidia (sea stars) –Ophiuroidea (brittle stars) –Echinoidea (sea urchins and sand dollars) –Crinoidea (sea lilies and feather stars) –Holothuroidea (sea cucumbers) –Concentricycloidea (sea daisies)

  42.                         Works Cited • Campbell, Neil A. Biology. [S.l.]: Benjamin-Cummings, 2005. Print.

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