Comprehensive Notes on Lower & Higher Invertebrates, Animal Characteristics, and Vertebrates

Lower Invertebrates

  • Cnidaria: Common name for organisms in Phylum Cnidaria.

  • Cnidocyte: Specialized stinging cells in cnidarians used for feeding and defense.

  • Nematocyst: Tiny barbed spear within the stinging cells of cnidarians.

  • Polyp: Body shape of cnidarians that has a tube shape with tentacles around the mouth and is sessile (immobile).

  • Medusa: Body shape of cnidarians that has an umbrella shape, tentacles around the mouth, and is motile (free-swimming).

  • Porifera: Phylum that contains organisms with collar cells, no tissues, and no nervous system.

    • Sponges: Common name for organisms in Phylum Porifera.

    • Collar cells: Specialized cells in poriferans that allow for filter feeding.

  • Platyhelminthes: Phylum that contains organisms that are acoelomates but have cephalization and a simple brain.

    • Flatworms: Common name for organisms in Phylum Platyhelminthes.

  • Nematoda: Phylum that contains organisms with a pseudocoelom and have cephalization and a simple brain.

    • Roundworms: Common name for organisms in Phylum Nematoda.

  • Cnidarians: Phylum that contains organisms with medusa or polyp body shapes, cnidocytes with nematocysts, and a nerve net.

Higher Invertebrates

  • Mollusca: Phylum that contains organisms with a foot, visceral mass, mantle, shell, radula, and that have cephalization.

    • Foot: Body part of a mollusk that is a broad muscular structure used for movement.

    • Visceral mass: Body part of a mollusk that contains the gills, gut, and other organs inside the coelom.

    • Mantle: Body part of a mollusk that covers the visceral mass and protects the body when there is not a shell present.

    • The mantle also covers the mantle and protects the body from drying out, sometimes not present

    • Shell: Body part of a mollusk that covers the mantle and protects the body when there is not a shell present.Protects the body from drying out, sometimes not present

    • Radula: Tongue-like structure with curved teeth used for feeding by some mollusks.

    • Gastropods: Type of mollusk with a single shell, a radula, and which typically lives on land; examples: slugs and snails.

    • Bivalves: Type of mollusk with a two-part, hinged shell that are typically filter feeders; examples: clams and other two-shelled shellfish.

    • Cephalopods: Type of mollusk with a complex nervous system and closed circulatory system, also agile swimmers; examples: squids and octopuses.

    • Open circulatory system: Type of circulatory system where the heart pumps blood through spaces (sinuses) in the body.

    • Closed circulatory system: Type of circulatory system where the heart pumps blood through a network of vessels that form a closed loop.

  • Annelida: Phylum that contains organisms with segmentation and cephalization, but do not have an exoskeleton.

    • Segmentation: Characteristic an organism has when there are repeated body segments.

  • Arthropoda: Phylum that contains organisms with an exoskeleton, jointed appendages, cephalization, and that go through metamorphosis.

    • Jointed appendages: Characteristic an organism has when the arms or legs have bendable joints.

    • Exoskeleton: An external skeleton that surrounds and protects the body.

    • Metamorphosis: A process in which an animal changes form as it develops from an embryo or larva to an adult.

  • Echinodermata: Phylum that contains organisms with an endoskeleton, water vascular system, and tube feet.

    • Endoskeleton: An internal skeleton that provides structure and support for the body.

    • Water vascular system: A system in echinoderms that uses water to help the animal move, eat, breathe, and sense the environment.

    • Tube feet: Tiny suckers that echinoderms have for feeding and movement.

Characteristics & Classification of Animals

  • Multicellular: Characteristic when an organism is made of 2 or more cells.

  • Sexual reproduction: Type of reproduction that requires 2 parents and produces offspring with a combination of genetic material from each of their parents.

  • Specialized cells: Cells that have specific functions to help support the life of the overall organism.

  • Movement: The ability all animals have at some point in their life cycle to change their position in an environment.

  • Heterotroph: Characteristic when an organism consumes other organisms to gain energy.

  • Endotherm: An organism that is able to maintain a stable body temperature despite fluctuations in environmental temperature.

  • Ectotherm: An organism whose body temperature depends on changes in the environmental temperature.

  • Invertebrate: Animal without a backbone.

  • Vertebrate: Animal with a backbone.

  • Symmetry

    • Asymmetry: Lack of symmetry.

    • Bilateral symmetry: Symmetry where the body can be divided equally along a single plane.

    • Radial symmetry: Symmetry where the body can be divided equally along any plane through a central axis.

  • Coelom: A body cavity that is fully-lined and contains the gut and organs.

    • Coelomate: Organism with a coelom.

  • Pseudocoelom: A body cavity that is not completely lined and is fluid filled.

    • Pseudocoelomate: Organism with a pseudocoelom.

  • Acoelomate: Organism with no coelom.

  • Ganglia: A group of nerve cells that control part of the body.

  • Cephalization: Concentration of sense organs to form a head region.

Vertebrates

  • Chordata: Phylum that contains vertebrates.

    • Chordates: Organisms that are members of Phylum Chordata.

    • Notochord: Cartilaginous structure in chordates that provides structure and support for the hollow nerve cord.

    • Vertebrae: Bony structure in vertebrates developed from the notochord.

    • Tail: Muscular structure that extends past the anus in chordates.

    • Hollow nerve cord: Nervous system structure in chordates found down the back of the organism which branches at regular intervals to connect to major organs.

    • Pharyngeal pouches: Paired structures in throat region that may develop into gills or other body parts.

  • Fishes: Organisms with fins, scales, and gills.

    • Fins: structure that fish use for movement

    • Scales: structures that cover and protect fish

    • Gills: structures that fish use for respiration in water

    • Swim bladder: Balloon-like organ filled with gases to help bony fish move in water.

  • Amphibians: Organisms that have a "double life", part in water and part on land.

    • Lungs: structure adult amphibians use for respiration on land

    • Cutaneous respiration: process used by amphibians to breathe through their skin.

    • Metamorphosis: Process of developmental change from larvae to adults that amphibians go through

  • Reptiles: Organisms that have thick skin, amniotic eggs, and are ectotherms.

    • Amniotic egg: Egg that does not need to be laid in water and prevents embryo from drying out.

  • Birds: Organisms that are endotherms and have feathers, lightweight bones, and beaks.

    • Feathers: structure birds have that helps maintain body temperature and helps with flight

  • Mammals: Organisms that are endotherms and have mammary glands, a diaphragm, and fur.

    • Mammary gland: Structure mammals have that provides nutritious milk to offspring.

    • Monotremes: type of mammal that lays eggs

    • Marsupials: type of mammal that gives birth to young that are not fully developed and raises them in a pouch

    • Placental mammals: type of mammal where the embryo remains inside the mother, developing in a uterus with a placenta that provides food and oxygen from the mother