BIO 1070 Exam 3 Study Guide: Animal Diversity and Phylogeny

Chapter 32: Introduction to Animals

General Characteristics of Animals

• Animals are multicellular, eukaryotic organisms that are heterotrophic (obtain food by ingestion).

• They lack cell walls and possess specialized tissues for various functions.

• Most animals reproduce sexually, with a dominant diploid stage.

• Development typically includes a zygote undergoing cleavage to form a blastula, which then becomes a gastrula.

• Animals may exhibit direct development (juvenile resembles adult) or larval development (distinct larval stage, followed by metamorphosis).

Animal Body Plans

• Symmetry: Animals may have radial symmetry (body parts arranged around a central axis) or bilateral symmetry (distinct left and right sides).

• Tissues: Animals are classified as diploblastic (two germ layers: ectoderm and endoderm) or triploblastic (three germ layers: ectoderm, mesoderm, endoderm).

• Body Cavities:

  • Coelomate: True body cavity completely lined by mesoderm.

  • Pseudocoelomate: Body cavity partially lined by mesoderm.

  • Acoelomate: No body cavity between digestive tract and outer body wall.

• Developmental Modes:

  • Protostome: Mouth develops from the blastopore; spiral, determinate cleavage.

  • Deuterostome: Anus develops from the blastopore; radial, indeterminate cleavage.

Clades and Classification

• A clade is a group of organisms that includes an ancestor and all its descendants (monophyletic group).

• Traditional classification may not always reflect evolutionary relationships, while clades are based on common ancestry.

Key Vocabulary

• Choanoflagellate: Closest protist relatives of animals.

• Heterotrophic: Organisms that obtain energy by consuming other organisms.

• Tissues: Groups of similar cells performing a common function.

• Asexual/Sexual reproduction: Modes of producing offspring without/with gamete fusion.

• Zygote, Cleavage, Blastula, Gastrula: Stages in early animal development.

• Direct/Larval development, Larva, Metamorphosis: Patterns and stages of animal development.

• Radial/Bilateral symmetry: Types of body symmetry.

• Protostome/Deuterostome: Major developmental modes.

• Diploblastic/Triploblastic: Number of embryonic germ layers.

• Coelom/Pseudocoelom/Acoelomate: Types of body cavities.

Chapter 33: Invertebrates

Overview of Invertebrate Diversity

Invertebrates are animals without a backbone, comprising the vast majority of animal species. They display a wide range of body plans, habitats, and life histories.

Major Invertebrate Phyla and Their Characteristics

Phylum	Main Characteristics	Examples	Subgroups	Clade
Porifera	Sessile, filter-feeders, lack true tissues	Sponges	None	Basal animals
Cnidaria	Radial symmetry, diploblastic, stinging cells (cnidocytes)	Jellyfish, corals, hydras	Polyp, Medusa	Eumetazoa
Platyhelminthes	Bilateral symmetry, acoelomate, often parasitic	Flatworms, tapeworms	Turbellaria, Trematoda, Cestoda	Lophotrochozoa
Rotifera	Pseudocoelomate, microscopic, wheel organ (corona)	Rotifers	None	Lophotrochozoa
Ectoprocta	Colonial, lophophore feeding structure	Bryozoans	None	Lophotrochozoa
Brachiopoda	Shells, lophophore, marine	Brachiopods	Inarticulate, Articulate	Lophotrochozoa
Mollusca	Soft body, mantle, muscular foot, radula	Snails, clams, squids	Gastropoda, Bivalvia, Cephalopoda	Lophotrochozoa
Annelida	Segmented worms, closed circulatory system	Earthworms, leeches	Polychaeta, Oligochaeta, Hirudinea	Lophotrochozoa
Nematoda	Roundworms, pseudocoelomate, cuticle, molting	Ascaris, C. elegans	None	Ecdysozoa
Arthropoda	Exoskeleton, jointed appendages, segmented body	Insects, spiders, crustaceans	Chelicerata, Myriapoda, Hexapoda, Crustacea	Ecdysozoa
Echinodermata	Radial symmetry (adults), water vascular system, tube feet	Sea stars, sea urchins	Asteroidea, Echinoidea, Holothuroidea, etc.	Deuterostomia

Key Vocabulary and Concepts

• Invertebrate: Animal lacking a backbone.

• Vertebrate: Animal with a backbone.

• Sessile: Fixed in one place; immobile.

• Sedentary: Tending to spend much time seated; somewhat mobile but not active.

• Parasitic: Lives on or in a host, causing harm.

• Filter-feeder: Feeds by straining suspended matter from water.

• Hermaphroditic: Having both male and female reproductive organs.

• Choanocytes: Flagellated cells in sponges for feeding.

• Amoebocytes: Mobile cells in sponges for digestion and structure.

• Polyp/Medusa: Two body forms in cnidarians.

• Cnidocyte/Nematocyst: Stinging cell and its organelle in cnidarians.

• Lophophore: Ciliated feeding structure in some lophotrochozoans.

• Trochophore larvae: Distinct larval stage in some lophotrochozoans.

• Marine/Terrestrial/Freshwater: Types of habitats.

• Parthenogenesis: Development of an egg without fertilization.

• Mantle, Visceral mass, Foot, Radula: Molluscan body parts.

• Parapodia: Paired appendages in polychaete annelids.

• Cuticle, Molting: Non-living covering and its shedding in ecdysozoans.

• Hydrostatic skeleton: Fluid-filled cavity for support.

• Exoskeleton: External skeleton for support and protection.

• Complete/Incomplete digestive tract: Digestive system with/without two openings.

• Open/Closed circulatory system: Blood flows in open spaces or closed vessels.

• Chelicerae, Pedipalps: Specialized appendages in arachnids.

• Book lungs, Trachea, Gills, Lungs: Respiratory structures in arthropods and mollusks.

• Water vascular system, Tube feet: Unique to echinoderms for movement and feeding.

Chapter 34: Phylum Chordata

Chordate Clade and Characteristics

• Chordates belong to the Deuterostomia clade.

• All chordates share the following characteristics at some point in development:

  • Notochord: Flexible, supportive rod along the back.

  • Dorsal, hollow nerve cord: Develops into the central nervous system.

  • Pharyngeal slits or clefts: Openings near the pharynx; function in feeding, respiration, or develop into structures in the head/neck.

  • Muscular, post-anal tail: Tail extending beyond the anus.

Subphyla of Chordata

Subphylum	Main Characteristics	Examples
Cephalochordata	Blade-like shape, retain all chordate features as adults	Lancelets
Urochordata	Larvae have chordate features; adults are sessile filter-feeders	Tunicates (sea squirts)
Vertebrata	Have a backbone (vertebral column), cranium, and endoskeleton	Fishes, amphibians, reptiles, birds, mammals

Main Groups of Vertebrates and Their Characteristics

• Jawless fishes (Agnatha): Lack jaws and paired fins (e.g., hagfish, lampreys).

• Cartilaginous fishes (Chondrichthyes): Skeleton made of cartilage (e.g., sharks, rays).

• Ray-finned fishes (Actinopterygii): Bony skeleton, fins supported by rays, swim bladder for buoyancy.

• Lobe-finned fishes (Sarcopterygii): Fleshy, lobed fins; ancestors of tetrapods.

• Amphibians: Moist skin, require water for reproduction (e.g., frogs, salamanders).

• Reptiles: Amniotic egg, scales, ectothermic (e.g., snakes, lizards, turtles).

• Birds: Feathers, endothermic, amniotic egg, adaptations for flight.

• Mammals: Hair, mammary glands, endothermic, differentiated teeth.

  • Monotremes: Egg-laying mammals (e.g., platypus).

  • Marsupials: Pouched mammals (e.g., kangaroo).

  • Eutherians: Placental mammals (e.g., humans, whales).

Key Vocabulary

• Notochord: Flexible rod for support in chordate embryos.

• Nerve cord: Dorsal, hollow structure; forms brain and spinal cord.

• Vertebral column: Series of vertebrae protecting the nerve cord.

• Endoskeleton: Internal skeleton made of bone or cartilage.

• Cranium: Skull protecting the brain.

• Cartilage: Flexible connective tissue.

• Ray-finned/Lobe-finned: Types of bony fishes based on fin structure.

• Swim bladder: Gas-filled organ for buoyancy in fishes.

• Operculum: Bony flap covering gills in bony fishes.

• Amniotic egg: Egg with protective membranes, allows reproduction on land.

• Endotherm/Ectotherm: Organisms that regulate body temperature internally/externally.

• Mammary glands: Milk-producing glands in mammals.

• Placenta: Organ for nutrient and waste exchange in placental mammals.

• Monotremes/Marsupials/Eutherians: Major groups of mammals based on reproductive strategies.