bio final

Kingdom Animalia

Multicellular, eukaryotic, heterotrophic organisms that lack cell walls.

Invertebrates

Animals without a backbone.

Vertebrates

Animals with a backbone, a subphylum within Chordata.

Body plans

• Sac-like: one opening (gastrovascular cavity).

• Tube-within-a-tube: complete digestive tract.

Diploblastic

Organisms with two germ layers (ectoderm and endoderm), such as cnidarians.

Triploblastic

Organisms with three germ layers (ectoderm, endoderm, mesoderm), typical of bilaterians.

Coelomate

Animals with a true body cavity fully lined with mesoderm.

Eucoelomate

true body cavity fully lined with mesoderm (annelids, molluscs, arthropods, chordates).

Pseudocoelomate

Animals with a body cavity that is not fully lined with mesoderm, such as roundworms.

Acoelomate

Animals with no body cavity, like flatworms.

Radial symmetry

Symmetry around a central axis, common in cnidarians.

Bilateral symmetry

Symmetry with a right and left side, correlated with cephalization.

Protostomes

Organisms that develop the mouth before the anus during embryonic development.

Deuterostomes

Organisms that develop the anus before the mouth during embryonic development.

Porifera (Sponges)

Cellular level of organization (no true tissues)

• Ostia (incurrent pores), osculum (exit).

• Spicules (CaCO₃ or silica) + spongin for support.

• Choanocytes (feeding), archaeocytes (digestion, reproduction).

• Mesohyl (gel matrix).

• Sessile filter feeders

• Reproduction: sexual & asexual; gemmules for dormancy.

• Canal systems: Asconoid, Syconoid, Leuconoid (most complex).

Cnidocytes

• Radial, diploblastic, true tissues.

• Body forms: polyp (sessile), medusa (free-swimming).

• Cnidocytes with nematocysts (stinging organelles).

• Gastrovascular cavity.

• Nervous system: nerve net.

• Planula larva.

Gastrovascular cavity

A central cavity in cnidarians used for digestion and distribution of nutrients.

Ctenophora

• Comb jellies

• Ctenes (cilia rows), colloblasts (sticky cells).

• Possible earliest-diverging animals.

Platyhelminthes (Flatworms)

• Bilateral, triploblastic, acoelomate.

• Cephalization, ladder-type nervous system.

• Excretion: flame cells + tubules.

• Ocelli, muscular pharynx.

Flukes (Trematodes)

• Complex life cycles with intermediate hosts.

• Stages: miracidium → sporocyst → redia → cercaria → metacercaria → adult.

• Examples: Clonorchis sinensis, Schistosoma.

Tapeworms (Cestodes)

• No digestive tract.

• Scolex, neck, proglottids.

• Life cycle via beef/pork.

Rotifera

• Corona (cilia), mastax (jaw), trophi (teeth).

• Parthenogenesis common

Trochophore larva

A free-swimming larval stage characteristic of some lophotrochozoan animals.

Annelida (Segmented Worms)

• Lophotrochozoans, eucoelomate, protostomes.

• Structures: chaetae, parapodia, prostomium, peristomium, nephridia, ventral nerve cord, closed circulation, peristalsis.

• Reproduction: trochophore, atoke/epitoke (polychaetes).

• Groups:

  • Polychaetes

  • Oligochaetes (earthworms): clitellum, cocoon, dorsal blood vessel

  • Leeches: hirudin, suckers, 3-part jaws

Mollusca

• Lophotrochozoan, eucoelomate, protostome.

• Body plan: head-foot, visceral mass, mantle, mantle cavity.

• Shell (3 layers), radula, gills, open circulation (except cephalopods).

• Countercurrent exchange, trochophore larva.

GastropodaSnails

• Snails, slugs, nudibranchs; univalve shell.

• Nudibranch: cerata, conotoxin.

Bivalvia

• Filter feeders; siphons, byssal threads, adductor muscles, hinge ligament.

• Larvae: trochophore, veliger.

Cephalopoda

• Octopus, squid, cuttlefish, nautilus.

• Chromatophores, ink sac, jet propulsion, pen, cuttlebone, siphuncle.

• Advanced nervous system, giant axons.

Nematoda

• Pseudocoelomate, cuticle, hydrostatic skeleton, longitudinal muscles, eutely.

• Parasites: hookworms, Trichinella, Wuchereria (filarial), Guinea worm.

Arthropoda

Exoskeleton, chitin, jointed appendages, hemocoel, molting, metamerism, tagmata, tracheae/spiracles, Malpighian tubules.

Chelicerae

Pinchers or fangs used for feeding in arachnids.

Crustaceans

• Biramous appendages, mandibles, maxillae, swimmerets, uropods.

• Includes barnacles, copepods, crabs, crayfish, lobsters.

Insects

• 3 pairs of legs, wings, diverse mouthparts.

• Respiration: tracheal system.

• Development:

  • Ametabolous (none)

  • Hemimetabolous (nymph)

  • Holometabolous (larva → pupa → adult)

Echinodermata

• Pentamerous radial symmetry (adult).

• Endoskeleton, water vascular system, tube feet, pedicellariae, dermal branchiae.

• Digestion: cardiac vs. pyloric stomach, digestive ceca.

Metamerism

The segmentation of body parts, seen in annelids and arthropods.

Amniotic egg

An egg containing membranes that protect the embryo; a key adaptation for reptiles.

Homocercal tail

A type of tail fin in fish where the upper and lower lobes are symmetrical.

Ectothermic

Organisms that rely on external sources to regulate their body temperature.

Altricial young

Young that are born in an underdeveloped state and require parental care.

Vestigial structures

Morphological features that have lost their original function through evolution.

Microevolution

Minor evolutionary changes within a population, often driven by genetic drift, mutation, and selection.

Symbiosis

A close and often long-term interaction between two different biological species.

Aposematism

The use of warning coloration to signal that an organism is toxic or unpalatable.

Chordata

• Notochord

• Dorsal hollow nerve cord

• Pharyngeal pouches/slits

• Postanal tail

Cephalochordates (lancelets)

retain all features as adults.

Urochordates (tunicates)

lose features as adults; tadpole larva, paedomorphosis.

Craniates & Vertebrates

• Skull, vertebral column replacing notochord (except hagfish).

• Well-developed senses, closed circulation, kidneys, sexual reproduction.

Fishes

Aquatic, gill breathing, ectothermic, fins, scales.

Agnathans

Lampreys; jawless, no paired fins; parasitic forms.

Gnathostomes

• Jaw derived from gill arches.

• Placoderms = extinct armored jawed fishes.

Chondrichthyes

Cartilaginous skeleton, placoid scales, oil-filled liver, strong senses, heterocercal tail.

Osteichthyes (Bony Fishes)

• Ray-finned – operculum, swim bladder, homocercal tail.

• Lobe-finned – fleshy fins; ancestors of tetrapods.

Tetrapods → Amphibians

• Require water for reproduction; jelly eggs.

• Frogs/toads: metamorphosis, 3-chamber heart, lungs, ectothermic.

Reptiles

• Amniotic egg, internal fertilization, dry scaly skin, uric acid.

• Includes turtles, snakes, lizards, crocodilians (4-chambered heart).

Birds (Aves)

• Hollow bones, feathers, high metabolism, air sacs, 4-chamber heart, endothermic.

• Altricial vs. precocial young.

Mammals

• Hair, mammary glands, endothermic, efficient lungs, large brain.

• Reproduction:

  • Monotremes – egg-laying

  • Marsupials – immature young in pouch

  • Placental mammals – most advanced development

Evolution

• Influenced by: climate, atmosphere, continental drift, volcanoes, meteorites.

• Mass extinctions (6 major) reset ecosystems.

Evidence for Evolution

Fossils, biogeography, homology, embryology, vestigial structures, molecular biology.

Microevolution

• Hardy-Weinberg conditions (no mutation, migration, drift, selection, random mating).

• Causes: mutation, gene flow, sexual selection, genetic drift (bottleneck/founder).

Natural Selection Types

Directional, stabilizing, disruptive, balancing.

Speciation

• Allopatric vs. sympatric.

• Adaptive radiation.

Bacteria

prokaryotes, cell walls (peptidoglycan).

Plants

multicellular autotrophs; cellulose cell walls.

Fungi

heterotrophic decomposers; chitin walls.

SPECIAL TOPICS

• Wall Lizards – adaptation studies.

• Symbiosis – Bobtail squid & bioluminescent bacteria.

• Fungi & Climate change – carbon cycling.

• Aposematism – warning coloration.

• Leucism – partial pigment loss (white squirrels).