Animal Biology

• Animals


  • Multicellular eukaryotes that lack cell walls
  • Have sensory organs, the ability to move, internal digestion, and sexual reproduction
  • Heterotrophs
• Animal phyla with the greatest number of species(has at least 10, 000 species)


  • Mollusca
  • Porifera
  • Cnidaria
  • Platyhelminthes
  • Nematoda
  • Annelida
  • Arthropoda
  • Echinodermata
  • Chordata
• Porifera (sponges)


  • Sessile (attached at the base)
  • Porous body
  • Suspension feeders
  • Mostly hermaphrodites
  • Sexually Reproduce
• Cnidaria


  • Radial symmetry
  • Cnidocytes (structure for capturing food)
  • Nematocyst (enable them to stick and entangle prey)
  • Single central gastrovascular cavity with one opening (mouth and anus)
• Platyhelminthes


  • Flat
  • No specialized organs for gas exchange or circulation
  • Ciliated cells called flame bulbs that maintain osmotic balance
• Nematoda (roundworms)


  • Cylindrical bodies coated with tough cuticles that are shed off periodically
  • Live in moist areas, even in body fluids of animals and plants
• Mollusca


  • Soft-bodied but most have hard shells made of calcium carbonate
  • Muscular foot for movement
  • Visceral mass containing most internal organs
  • Mantle that drapes over visceral mass and secretes shell
• Annelida


  • Clitellum (important organ that secrets a mucous cocoon during reproduction)
  • Some can reproduce asexually by fragmentation followed by regeneration
• Arthropoda


  • Jointed legs
  • Segmented coelomates with exoskeleton and jointed appendages
  • Appendages specialized for walking, feeding, sensory reception, and copulation
  • Exoskeleton made of layers of protein and chitin covered with cuticles
  • Provides protection and attachment of muscles for movement
  • Exoskeleton is shed off during molting/ecdysis
  • Open circulatory system, most insects have tracheal system for gas exchange
• Echinodermata


  • Thin skin covering endoskeleton of hard calcareous plates
  • Water vascular system branching into tube feet that function in locomotion, feeding, and gas exchange
• Vertebrates


  Have a backbone
• Invertebrates


  Do not have a backbone
• Chordates


  Include both vertebrates and invertebrates
• Innate behaviors


  Instinctive, controlled by genes, always occur the same way
• Instinct


  Ability of an animal to perform a behavior for the first time it is exposed to the proper stimulus
• Reflex


  Response that always occurs when a certain stimulus is present
• Learning


  Change in behavior that occurs as a result of experience
• Learned behaviors


  Adaptive and flexible, can change if the environment changes
• Society


  Close-knit group of animals of the same species living together
• Social animals


  Animals that live in a society and live and work together for the good of the group
• Cooperation


  Animals in a society working together, each having a specific role
• Ways animals communicate


  • Sounds
  • Chemicals
  • Visual cues
• Pheromones


  Chemicals used by ants and male dogs to communicate and mark territory
• Aggression


  Behavior intended to cause harm or pain, often occurs when individuals compete for the same resources
• Types of competition


  • Intraspecific (between members of the same species)
  • Interspecific (between members of different species)
• Circadian rhythms


  Regular changes in biology or behavior that occur in a 24-hour cycle
• Migration


  Seasonal movements of animals from one area to another, usually to find food or mates
• Mating


  Union of a male and female of the same species for reproduction
• Females


  More selective than males in choosing mates
• Courtship displays


  Performed by males to encourage females to choose them as mates
• Invertebrates


  Majority of living animals, lack a backbone
• Invertebrate digestive systems


  • Incomplete (one opening serving as both mouth and anus)
  • Complete (two openings, mouth and anus)
• Larva


  Juvenile, immature stage of an animal that is quite different in form and function from the adult
• Fission


  Process where an animal divides into two parts, each part then regrows the missing part

  Example: Worms
• Most invertebrates reproduce sexually
• Budding


  Parent forms a small bump or bud, the bud remains attached to the parent while it develops into a new individual

  Example: Corals
• Eight major phyla of invertebrates


  • Porifera (sponges)
  • Cnidaria (jellyfish, corals)
  • Platyhelminthes (flatworms, tapeworms, flukes)
  • Nematoda (roundworms)
  • Mollusca (snails, clams, squids)
  • Annelida (earthworms, leeches, marine worms)
  • Arthropoda (insects, spiders, crustaceans, centipedes)
  • Echinodermata (sea stars, sea urchins, sand dollars, sea cucumbers)
• Porifera


  • Multicellular, specialized cells but no tissues, asymmetry, incomplete digestive system
• Cnidaria


  • Radial symmetry, true tissues, incomplete digestive system
• Platyhelminthes


  • Cephalization, bilateral symmetry, mesoderm, complete digestive system