Animals II: The Protostomes and Deuterostomes

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Animals II: The Protostomes and Deuterostomes
2012-04-04 20:31:39
Bio 244 lab

Unit 19
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  1. Protostomes include:
    phyla annelida, mollusca, arthropoda
  2. Deuterostomes include:
    phyla echinodermata, chordata
  3. Both protostomes and deuterostomes share this body plan:
    • eucoelomate
    • triploblastic
    • bilaterally symmetrical
  4. Protostome
    Fate of the blastopore
    becomes the mouth
  5. Deuterostome
    Fate of the blastopore
    becomes the anus
  6. Protostome
    Division cleavage
    spiral cleavage
  7. Deuterostome
    Division cleavage
    radial cleavage
  8. Protostome
    Cell differentiation cleavage
    • determinate cleavage - the developmental fate of each cell determined early on
    • if a zygote is split, it will become two halves of an embryo; the blastomeres will give rise to two different parts of the body
  9. Deuterostome
    Cell differentiation cleavage
    • indeterminate cleavage - fates of the blastomeres do not become fixed until later on in development
    • can create identical twins from one fertilized egg
  10. Protostome
    Coelom formation
    • schizocoelom
    • solid masses of mesoderm form near the blastopore; these masses split open, forming a fluid-filled body cavity
  11. Deuterostome
    Coelom formation
    • enterocoelom
    • masses of mesodermal cells bud off of the wall of the archenteron to form the enterocoelom
  12. Phylum Annelida
    body plan characteristics
    • triploblastic, eucoelomate, bilaterally symmetrical
    • cephalization
    • protostome
    • segmentation; metamerism
  13. metamerism
    • serial repetition of compartments
    • metameres - the identical body compartments, along with their appendages
    • an important evolutionary attribute becasue it allowed specialization of body parts
  14. digestive systems (annelids)
    • extracellular digestion
    • typhlosole - ridgelike fold of the side of the intestine into the lumen; increases surface area
    • chloragogue cells function in storing carbohydrates and lipids, and maybe excretion
  15. osmoregulatory/excretory systems (annelids)
    • posses metanephridia - tubules that open at two ends (one to outside, one to coelom)
    • filtrate is collected via the nephrostome and eliminated outside via the nephridiophore
  16. protonephridia vs. metanephridia
    • protonephridia - no opening on the inside of the body; flame cells in the protonephridium causes the filtrate to move outward; essentially osmoregulatory organs (flatworms, rotifers, roundworms)
    • metanephridia - larger, more complex structures that often function in both excretion and osmoregulation; 2 openings
  17. circulatory and respiratory systems (annelids)
    • closed circulatory system; allow for more efficient and rapid transport of blood
    • leeches are exception with an open circulatory system - blood is found in blood-filled sinuses or cavities
    • gas exchange is through diffusion across body wall
  18. nervous systems (annelids)
    • monoecious or dioecious
    • fertilization is external, occurring in the water column or inside a cocoon
    • larvae of marine species are called trochophores, which metamorphose into adults
  19. muscular systems (annelids)
    circular and longitudinal bands of muscle present
  20. integumentary and skeletal systems (annelids)
    • epidermis produces the cuticle
    • muscles are able to affect locomotion and digestion by contracting against the fluid filled coelom (acts as hydrostatic skeleton)
  21. parapodium
    • serve as locomotion and breathing apparatuses in annelids
    • acicula - connected to body wall muscles; help the parapodia move
  22. Phylum Mollusca
    body plan characteristics
    • triploblastic
    • eucoelomate
    • bilaterally symmetrical
    • cephalization (with exception of bivalves)
    • protostomes
    • 4 distinct body parts present - foot, mantle, shell, visceral mass
  23. 4 distinct body parts in molluscs
    • muscular foot
    • calcareous shell (secreted by mantle)
    • mantle - part of the skin, adapted to prevent excessive water loss
    • visceral mass - contains the digestive and reproductive systems
  24. integumentary and skeletal systems (molluscs)
    • calcareous shell
    • a ciliated epidermis creates a thin cuticle (composed of the protein conchin)
    • three layers of smooth muscle - outer circular layer, diagonal layer, inner longitudinal layer
    • hydrostatic skeleton
  25. muscular systems and locomotion (molluscs)
    • large muscular foot
    • glide through a layer of mucus (produced by the epidermis) by ciliary action
    • muscular contractions that sweep along the bottom of the foot
    • cephalopods and some bivalves can use jet propulsion by expelling water out of the mantle cavity
  26. digestive systems (molluscs)
    • extracellular digestion
    • complete tract
    • radiula - chitinous ribbon of teeth that scrapes food off of substrates
  27. osmoregulatory/excretory systems (molluscs)
    • large metanephridia (like the annelids)
    • eliminate mostly ammonia; some land snails can convert ammonia to uric acid
    • osmoconformers or osmoregulators
  28. osmoconformer
    • body fluids are iso-osmotic to seawater
    • includes some marine molluscs and most previous observed phyla
  29. osmoregulators
    • body fluids remain hyperosmotic compared to their environments
    • ability to regulate many ions
    • includes many aquatic molluscs and land snails
  30. circulatory systems (molluscs)
    • open circulatory system with a large hemocoel (blood filled cavity)
    • cephalopods - closed circulatory system with one systemic heart and auxiliary branchial hearts
    • includes forms of hemoglobin
  31. nervous systems (molluscs)
    • brain and one or more ventral nerve cords
    • sensory receptors (light, chemical, current) are foundi n various places of the body
    • unidirectional movement of action potentials (like annelids, flatworms)
    • advancements in nervous system sturcutre and function allow annelids and molluscs to be capable of more complex behaviors, compared to flatworms and cnidarians
  32. respiratory systems (molluscs)
    • gills for gas exchange
    • gastropods may have secondarily evolved a lung
    • respiratory pigments (hemoglobin) present
  33. reproductive systems (molluscs)
    • monoecious or dioecious, internal or external fertilization, depending on species
    • may have free-swimming trochophore larva, which develops into other larval stages before settling and metamorphosing into adults
  34. immune systems (molluscs)
    • exhibit a non-specific immunity against potential invading microorganisms
    • integument is primary barrier to pathogens
    • internal wandering amebocytes that phagocytize foreign cells and particles
  35. gas exchange (molluscs)
    • bivalves - walls (lamellae) have a series of ridges (gill filaments); water flows past the gill filaments due to the activity of the numverous cilia along the filaments
    • pulmonate gastropods - mantle makes an interior fold called the lung
    • gas exchange also occurs across the skin, esp on the mantle
  36. Phylum Arthropoda
    body plan characteristics
    • tirploblastic
    • eucoelomate; coelom is reduced to a body cavity called the hemocoel
    • bilaterally symmetrical
    • cephalization
    • protostomes
    • segmented; segments form tagmata
  37. tagmata
    • segments that are fused together
    • regional formation of body parts that are specialized and highly adaptive; tagmata are involved in locomotion (thorax), sensation and feeding (head), or visceral activities of reproduction, excretion, and digestion (abdomen)
    • arachnids (chelicerata) - two tagmata; cephalothorax and abdomen
    • crustaceans - two tagmata; cephalothorax and abdomen
    • uniramians include centipedes, millipedes, insects
    • centipedes, millipeds - two tagmata; head and body
    • insects - three tagmata; head, thorax, abdomen
  38. muscular systems (arthropods)
    • jointed appendages that are made of segments called podomeres
    • have specialized functions
  39. integumentary and skeletal systems (arthropods)
    • exoskeleton composed of the polysaccharide chitin
    • protects the animal against disease, predators, dessication, provides sites for muscle attachment
    • periotic ecdyses (molts) allows the animal to grow larger
    • produced by the epidermis
  40. digestive systems (arthropods)
    • extracellular digestion occurs within the lumen of the gut
    • complete tract
    • mechanical digestion, storage, chemical digestion, and nutrient absorption occur in sequential sections
  41. osmoregulatory/excretory systems (arthropods)
    • well-developed
    • either green antennal glands or Malpighian tubes
  42. green (antennal) glands
    • crayfish
    • type of neprhidium that excretes large amounts of ammonia and water
  43. Malpighian tubes
    • terrestrial arthropods
    • dump nitrogenous wastes and water into the gut; reabsorb water
    • uric acid is crystalized and eliminated
    • not a type of nephridium; it is closed on one end
    • because of the relative insolubility and savings from decreasing water loss, arthorpods have much more successfully colonized land
  44. circulatory and respiratory systems (arthropods)
    • open circulatory system with tubular heart and blood vessels; hemolymph
    • gills (aquatic insects and crustaceans)
    • trachea (most insects) - series of tubes that run throughout the body; oxygen diffuses
    • book lungs (spiders)
  45. nervous systems (arthopods)
    • anterior brain
    • paired central nerve cord
    • lateral nerve for appendages, etc.
  46. reproductive systems (arthropods)
    • dioecious; internal fertilization
    • metamorphosis is hallmark
    • in many insect species, the larval stages are adpated for a different habitat than the adult
  47. immune systems (arthropods)
    • like annelids and molluscs
    • non-specific immunity consisting of exoskeleton and wandering amebocytes
  48. gradual metamorphosis
    • egg - nymph - adult
    • nymphs are similar to adults
  49. complete metamorphosis
    • egg - larvae - pupae - adult
    • dramatic change in body plan occurs
  50. Phylum Echinodermata
    body plan characteristics
    • deuterostome
    • all marine
    • sessile
    • radially symmetrical as adults, bilaterally symmetrical as larvae
    • triploblastic
    • no segmentation
  51. integumentary systems (echinoderms)
    • dermal endoskeleton made of a series of calcareous plates (ossicles) and spines
    • some classes have pincer-like pedicellariae on their outer surface that prevent small organisms from from settling on the body surface (asteroidea, holothuroidea, crinoidea)
  52. skeletal systems (echinoderms)
    • a part of the coelom forms a series of water-filled canals and cavities collectively called the water vascular system
    • acts as a hydrostatic skeleton
    • helps move tube feet used in prety capture and locomotion
    • brittle stars do not have suckers on their tube feet
  53. digestive systems (echinoderms)
    • extracellular digestion
    • complete tract (except for brittle stars, lost their intestines and anus)
  54. excretory, respiratory, circulatory systems (echinoderms)
    • not extensive
    • metabolic wastes (primarily ammonia) diffuse directly across the body wall
    • finter-like extensions off the epidermis called dermal branchiae serve as sites for respiratory gas exchange
  55. nervous systems (echinoderms)
    • do not exhibit cephalization
    • nerve net (analogous to cnidarians)
    • sensory systems are reduced
  56. reproductive systems (echinoderms)
    • dioecious
    • external fertilization
    • larvae are planktonic organisms that feed inthe open waters
    • most echinoderm larvae metamorphose into sessile adults
  57. immune systems (echinoderms)
    possess wandering phagocytic cells