animalia

• Domain Eukarya: Kingdom Animalia

  Evolved from heterotrophic protistan ancestor
• Kingdom Animalia

  • Multi-cellular heterotrophs that move about to obtain food from external sources
  • They ingest first and then digest internally
  • They require some form of nervous system that responds to stimuli
  • They are herbivorous, omnivorous and carnivorous; some are ecto- or endoparasites
  • Life cycle is diploid dominated
• Animal classification

  • Based largely on anatomical features
  • The extent to which they have specialised tissues and organs
  • The type of body symmetry they have
  • Incomplete (sac-like) or complete (tube-like) digestive system
  • The possession of a body cavity (coelom)
  • How the embryo divides
  • Segmented or unsegmented body
  • Nerve chord and backbone or not
• Animalia descended from a single common ancestor
• Animalia


  • Two main branches, the vertebrates and invertebrates
  • Vertebrates have a spinal cord (a backbone)
  • Invertebrates do not have a backbone
• Characteristics of animals


  • Animals are mobile, have nerve and muscles
  • They reproduce sexually
  • Animals have variety of lifecycles
  • Many reproduce sexually and some reproduce asexually
  • Animals undergo a series of developmental stages to produce organisms with specialised tissues
  • Muscle and nerve tissues allows for motility and flexibility
  • Coordinated movement allow animals to seek mates and shelter
• Animal phyla of relevance to human health

  • Cnidaria (e.g. jellyfish, anemones and corals)
  • Platyhelminthes (flatworms) such as blood flukes (e.g. Schistosoma) and tapeworms (e.g. Taenia)
  • Nematoda (roundworms) such as Ascaris
  • Annelida (segmented worms) such as leaches
  • Mollusca (e.g. snail vector for Schistosoma; toxic shellfish)
  • Arthropods (=jointed legs) e.g. fleas, ticks, mites, insect vectors, scorpions
  • Chordata – include poisonous snakes and dangerous predators (e.g. big cats, bears, crocodiles, sharks). Can also act as secondary host (e.g. pigs and cows carrying tapeworms)
• Phylum Cnidaria


  • Around 9000 species
  • Almost all marine, a few are freshwater
  • Have stinging cells on tentacles – cnidocytes (also called nematocyts)
  • Body a two-layered sac with two basic tissue types – ectoderm and endoderm – and a simple network of nerves. No organs
  • Physalia (left) has a gas-filled float that also acts as a sail to help it move around
• Cnidocytes/Nemotocyts


  • The stinging cells are capsules with tubular threads that can be discharged like a harpoon
  • They produce protein toxins to protect themselves and immobilise prey such as small fish and shrimps
• Phylum Platyhelminthes


  • Around 13000 species living in water or wet soil
  • Some are free-living but most are parasitic flukes or tapeworms
  • They have a sac-like gut and basic organs but no coelom (= acoelomate)
  • They are bilaterally symmetrical and exhibit cephalization with a very simple brain
• Tapeworms


  • Live mostly inside vertebrates
  • Head (scolex) modified for attachment to intestinal wall of host
  • Lack a mouth and gastrovascular cavity
  • Body made of up of segments (proglottids) containing male and female reproductive organs that produce eggs that leave host's body in faeces
• Phylum Nematoda (roundworms)


  • Extremely common and found in almost all environments
  • Non-segmented, tubular gut and have a pseudo-coelom
  • Around 90 000 species
  • A number are important parasites of humans such as Ascaris
• Ascaris the parasitic nematoda
• Phylum Annelida (segmented worms)


  • 12 000 species
  • Segmented – body divided up into segments that divide the coelom
  • Organs repeated in each segment and have a hydrostatic skeleton
  • Some are ectoparasites such as the medicinal leach Hirudo medicinalis
• Phylum Arthropoda


  • More than 1 million species are known
  • Most successful group of organisms on earth
  • Play several roles regarding human health: Parasites e.g., fleas, mites and ticks
  • Vectors of disease e.g., Anophales and Glossina
  • Cause allergies e.g., house dust mite
  • Poisonous e.g., Loxodes (spider), Androctonus (scorpion)
• Vertebrates


  Members of phylum Chordata
• Vertebrates


  • Have bilateral symmetry
  • They are deuterostomes – anus develops prior to the mouth
  • Have internal skeleton made of bone or cartilage
  • Great movement and growth
  • Presence of vertebral column
• Chordates


  • All chordates have four derived traits that appear at some point during their development
  • Notochord- a supporting rod just below the nerve chord
  • Dorsal tubular nerve cord- a tubular cord situated dorsally
  • Pharyngeal pouches- seen during embryonic development in most vertebrates
  • Post anal tail- a tail in the embryo or adults
• Vertebral column


  • The embryonic notochord is replaced by a vertebral column
  • Remnants of the notochord give rise to the intervertebral disc
  • The vertebral column is a part of flexible but strong endoskeleton
  • This gives evidence that vertebrates are segmented
• Skull


  • The main axis of the internal skeleton consists of the vertebral column and a skull
  • The skull enclose and protects the brain
  • The brain of vertebrates is complex
  • The high degree of cephalisation is accompanied by complex sense organs
  • The ears function as sound wave receivers in land vertebrates
  • Developed sense of smell and taste
• Endoskeleton


  • Vertebrate skeleton is a living tissue that grows with the animal
  • Protects the internal organs
  • Serves as a place of muscle attachment
  • Two pairs are seen in vertebrates
  • Fishes have pectoral fin and a pelvis fin
  • Tetrapods have four limbs
  • Tetrapods are terrestrial vertebrates
• Internal organisation


  • Large coelom and complete digestive tract
  • Closed circulatory system
  • The respiratory system consist of gills and lungs
  • The kidneys are excretory and water regulating organs
  • Separate sex
  • Sexual reproduction
• Phylum Chordata


  Class Reptilia – some poisonous
• Vertebrates


  Members of phylum Chordata
• Vertebrates


  • Have bilateral symmetry
  • They are deuterostomes – anus develops prior to the mouth
  • Have internal skeleton made of bone or cartilage
  • Great movement and growth
  • Presence of vertebral column
• Chordates


  • All chordates have four derived traits that appear at some point during their development
  • Notochord- a supporting rod just below the nerve chord
  • Dorsal tubular nerve cord- a tubular cord situated dorsally
  • Pharyngeal pouches- seen during embryonic development in most vertebrates
  • Post anal tail- a tail in the embryo or adults
• Vertebral column


  • The embryonic notochord is replaced by a vertebral column
  • Remnants of the notochord give rise to the intervertebral disc
  • The vertebral column is a part of flexible but strong endoskeleton
  • This gives evidence that vertebrates are segmented
• Skull


  • The main axis of the internal skeleton consists of the vertebral column and a skull
  • The skull enclose and protects the brain
  • The brain of vertebrates is complex
  • The high degree of cephalisation is accompanied by complex sense organs
  • The ears function as sound wave receivers in land vertebrates
  • Developed sense of smell and taste
• Endoskeleton


  • Vertebrate skeleton is a living tissue that grows with the animal
  • Protects the internal organs
  • Serves as a place of muscle attachment
  • Two pairs are seen in vertebrates
  • Fishes have pectoral fin and a pelvis fin
  • Tetrapods have four limbs
  • Tetrapods are terrestrial vertebrates
• Internal organisation


  • Large coelom and complete digestive tract
  • Closed circulatory system
  • The respiratory system consist of gills and lungs
  • The kidneys are excretory and water regulating organs
  • Separate sex
  • Sexual reproduction
• Phylum Chordata


  Class Reptilia – some poisonous
• Reptiles


  • Thought to have evolved from lizards as an adaptation to burrowing
  • Some have toxic saliva to immobilize prey e.g., SA's Black Mamba (left)
  • Dendroaspis polylepis
  • Hollow needle-like fangs that deliver toxin from special glands – destroy blood vessels and tissue of victim
• Black and white spitting cobra

  • Paralyzes its victims with a potent venom
  • The venom is also a source of the drug called Immunokine
  • This drug is approved in Thailand
  • Used to treat side effects of cancer
• Black mamba venom


  • Contains compound called mambalgin
  • These compounds block pain signal
  • Inhibit flow of certain ions through nerves that carry pain message
  • Effective as morphine but not clinically used and approved
• Epibatidine


  • Derived from Ecuadorian poison dart frog
  • 50 to 200 times more powerful than morphine
  • In relieving chronic acute pain
  • Have serious side effects
  • Companies have synthesized compounds with similar structure
• Eptifibatide


  • Derived from pigmy rattlesnake found in Southeastern United State
  • It binds to blood platelets
  • Reduce their tendency to clump together
  • Used to reduce risk of blood clot
  • Venom of pit vipers contain clot busting substances
• Squalamine


  • A steroid like molecule that was first isolated in the liver of dog fish shark
  • Has broad antimicrobial properties
  • It can inhibit abnormal growth of new blood vessels
  • Can be used in eye treatment
  • Currently tested as a potential treatment for macular regeneration