Skip to main content
Back

General Biology: Animal Phyla and Characteristics

Control buttons has been changed to "navigation" mode.
1/20
  • Porifera (Sponges)

    Simplest animals with no true tissues; filter feeders drawing water through pores into a central cavity (spongocoel) and out the osculum.

  • Porifera cell types

    Choanocytes are flagellated cells that engulf bacteria by phagocytosis; amoebocytes perform metabolic processes.

  • Porifera reproduction

    Most are hermaphrodites; cross-fertilization occurs by releasing sperm into water, preventing self-fertilization.

  • Cnidarian body plan

    Sac with a gastrovascular cavity and a single opening serving as mouth and anus; two forms: polyp (sessile) and medusa (motile).

  • Cnidarian symmetry and tissues

    Radially symmetrical and diploblastic, having ectoderm and endoderm layers with simple contractile tissues and nerves.

  • Platyhelminthes (Flatworms) characteristics

    Triploblastic but lack a body cavity; flat shape allows gas exchange by diffusion; have a gastrovascular cavity with one opening.

  • Nematoda (Roundworms) features

    Covered by a tough cuticle that is shed as they grow; have a complete digestive tract and a pseudocoelom (hemocoel).

  • Annelids (Segmented worms)

    Segmented body with a coelom; complete digestive system; earthworms are hermaphrodites that cross-fertilize and can reproduce by fragmentation.

  • Mollusca body plan

    Muscular foot for movement, visceral mass with organs, and mantle that secretes a shell; most have a radula for feeding.

  • Mollusk classes

    Chitons (scrape algae), gastropods (snails with spiral shells), bivalves (two-part shells, no radula), cephalopods (predators with tentacles and closed circulatory system).

  • Arthropoda key traits

    Segmented body, chitin exoskeleton, jointed appendages, well-developed sensory organs, open circulatory system.

  • Arthropod groups

    Arachnids (4 walking legs, 2 chelicerae), myriapods (millipedes and centipedes), crustaceans (2 antennae, pinchers), insects (3 body regions, wings, metamorphosis).

  • Echinoderm characteristics

    Radial symmetry with 5 spokes, water vascular system with tube feet for locomotion and feeding, separate sexes releasing gametes into water.

  • Chordate defining features

    Notochord, dorsal hollow nerve cord, pharyngeal slits, and muscular post-anal tail.

  • Chordate symmetry and body plan

    Bilateral symmetry, coelom, segmented bodies; deuterosomes with anus developing first.

  • Vertebrates

    Chordates with a backbone; include jawless fish (hagfish, lampreys) and jawed vertebrates (gnathostomes).

  • Gnathostomes

    Vertebrates with jaws; include Chondrichthyes (cartilaginous fish), Actinopterygii (ray-finned fish), and Dipnoi (lungfish).

  • Tetrapods

    Gnathostomes with limbs; amphibians have moist skin for gas exchange and live in water as larvae and land as adults.

  • Amniotes

    Tetrapods with terrestrially adapted eggs; include reptiles (with amniotic eggs and rib cage ventilation) and mammals.

  • Mammals

    Amniotes with hair and milk production; evolved from synapsid ancestors; include monotremes, marsupials, and placental mammals.