Organismal Biology — Notes

STUDY GUIDE and VOCABULARY
FUNCTIONAL TOPICS / DEUTEROSTOMES / BEHAVIOR

  • STRUCTURAL AND FUNCTIONAL REQUIREMENTS:
  • GENERAL THINGS TO KNOW:
    • Describe the differences between intracellular and extracellular digestion, and between mechanical and chemical digestion
    • Describe the advantages of "assembly line" digestion in higher animals
    • Describe some general differences between exoskeletons, endoskeletons, and hydrostatic skeletons
    • Describe some differences between cartilage and bone
    • Describe how bone tissue can grow, remain alive, and heal following injury
    • Describe the major types of muscle tissue
    • Describe the overall organization of vertebrate nervous systems
    • Describe how the process of gas exchange takes place in various animals
    • Explain how materials are transported around the body in various animals
    • Describe how different animals rid their bodies of waste products

  • Nutrition in Animals
    Unicellular organisms ingest food by phagocytosis.
    Intracellular digestion predominates in lower animals.
    Extracellular digestion predominates in higher animals.
    • Mechanical digestion: Food is minced or crushed, exposing more surface area.
    • Chemical digestion: Food is broken down chemically with the help of enzymes.


    "Assembly line" (mouth-to-anus) digestion allows regional specialization to evolve, so that digestion happens in stages.


    Organization of vertebrate digestive systems:
    • Mouth:   Major site of mechanical digestion (using teeth, etc.). Chemical digestion begins with amylase enzyme in saliva that breaks down starches. Food passes from mouth to stomach via the esophagus.
    • Stomach:   Major site of protein digestion. Pepsin breaks proteins into small peptides. Hydrochloric acid (HCl) acidifies stomach contents, which helps pepsin, whose pH optimum is near 2.0. Mechanical digestion also occurs by contraction of 3 muscle layers, kneading food. Some species (like birds) have a large storage crop, followed by a strong muscular gizzard, specialized for mechanical digestion.

    • Liver:   Secretes bile, containing bile pigments (derived from hemoglobin) and bile salts, which emulsify fats. Bile is stored in the gall bladder until needed.
    • Small intestine:   Long and coiled, with large surface area.
      • Duodenum:   Digestion of lipids, carbohydrates, and proteins, using enzymes secreted by the duodenum itself and by the pancreas.   Lipids are emulsified by bile salts secreted by the liver.
      • Jejunum:   Chemical digestion of most nutrients completed here.
      • Ileum:   Site of most absorption of digestion end-products.
    • Large (large-diameter) intestine:   Includes:
      • Caecum (size varies): site of microbial digestion of cellulose in herbivores
      • Colon: site of much water resorption
    • Anus:   Undigested wastes are eliminated.


  • Skeletal Systems:
    Hydrostatic skeleton (as in many worms): a series of fluid-filled body cavities (coelomic cavities) can form a skeleton. Such a skeleton can be very useful in burrowing through loose sand of soil: those segments contricted by circular fibers protrude forward and lengthen the body, while segments compressed along the body axis by longitudinal fibers bulge sideways and anchor those parts of the body against slipping backward.

    Exoskeleton (as in insects and other arthropods): body parts are hollow, with hardened tissue on the outside. In small organisms (most insects, spiders), exoskeletons can be made of chitin, but in larger organisms (lobsters), chitin layer is usually strengthened by calcium salts.
    • Muscles are arranged on the inside, spanning joints. Most muscles span one joint at a time.
    • The weight of the exoskeleton limits its size, especially on land.
    • Growth is a problem once the skeleton hardens, so animals with exoskeletons molt at certain intervals: the animal cracks through and sheds its skeleton, exposes a new skeletal layer underneath, inflates its body, and allows its new, larger skeleton to harden.
    Endoskeleton: a skeleton on the inside, as in vertebrates. Muscles are arranged surrounding the bones of the skeleton. Animals with endoskeletons are generally larger than those with exoskeletons. Growth is less of a problem because skin can remain flexible.

    Area-volume relationships: Skeletal proportions (and therefore body proportions) are often dictated by area-volume relationships, which limit body shapes and sizes:
    • Mass and muscle strength are both related to volume.
    • Efficiency of digestion, respiration, or heat exchange are related to surface area, so large animals need more heavily folded surfaces.
    • Strength of supporting legs is related to cross-sectional area, while the weight needing support is related to volume. Thus, large animals (elephants, brontosaurs) need disproportionately thicker, cylindrical, and more vertical legs.
    VERTEBRATE SKELETON The skeleton contains both bone and cartilage tissues.
    Most cartilage later turns to bone.

    Cartilage tissue: not as strong as bone, but resists shock better. Smoother surface is better at moving joints. No blood supply; cells nourished by diffusion only. Grows much more rapidly than bone, until diffusion cannot meet nutritional needs; then cells die or are replaced by bone.

    Bone tissue: stronger than cartilage, but less resistant to shock and grows more slowly. Internal blood supply nourishes interior and keeps cells alive, allowing constant restructuring, repair, and healing of injuries.

    Compact (lamellar) bone tissue: made of layers, usually organized as Haversian systems (concentric cylinders surrounding a central Haversian artery). As bones restructure, new Harversian systems align parallel to greatest stress.

    Spongy (cancellous) bone tissue: built of struts (trabeculae) separated by spaces containing blood or marrow.

    Bone growth: there are two types of bone growth (ossification):
    • Dermal (intramembranous) ossification, within the dermis of the skin, forming membrane bones (clavicle, bones of skull roof & palate)
    • Endochondral ossification: pre-shaped or preformed as fast-growing cartilage tissue; bone then replaces the cartilage
      • Visceral bones, derived from gill arches: alisphenoid; malleus, incus, stapes; hyoid apparatus; cartilages of the larynx and trachea
      • Somatic bones, derived from embryonic somites:
        • Axial (derived directly from somites): braincase (ethmoid, sphenoid, occipital series), vertebrae, ribs, sternum
        • Appendicular (derived via limb bud mesenchyme): scapula, coracoid, humerus, radius, ulna, bones of wrist and hand; innominate bone (pelvic girdle), femur, tibia, fibula, bones of ankle and foot

    Growth of long bones:
    • Cartilage first grows in all directions.
    • A primary ossification (diaphysis) then forms in the middle of the bone
    • A secondary ossification (epiphysis) forms at either end.
    • An epiphyseal cartilage between diaphysis and epiphysis marks the region of fastest growth.
    • The growing diaphysis gradually replaces the epiphyseal cartilage.
    • Bone growth ceases when epiphyseal fusion is complete.


  • Muscles:
    Muscle tissues are specialized for contraction.
    Contractuion results from the sliding of thin filaments of actin lengthwise between thick myosin filaments.
    • Smooth muscle:   involuntary cells with tapering ends but no cross-banding; smooth, rhythmic contractions; nuclei located centrally; occurs in digestive organs, reproductive organs, etc.
    • Cardiac muscle:   involuntary fibers with cross-striations; cylindrical in shape but branching and coming together repeatedly; nuclei located centrally; cell boundaries marked by intercalated disks; rhythmic contractions; occurs in heart only
    • Skeletal muscle:   voluntary cells with cylindrical shape; cross-striations caused by alignment of actin and myosin fibers; many nuclei per fiber; no cell boundaries (each fiber is thus called a syncytium); rapid, forceful contractions, but fatigues easily; occurs in muscles; always attaches to connective tissues
    Individual muscles are organs made of many tissues.
    • The belly or fleshy part contains skeletal muscle tissue surrounded by layers of connective tissue (and also blood vessels and nerve endings).
    • Connective tissue usually extends beyond the belly to form tendons.
    • Most muscles span at least one joint.
    • A muscle that bends a joint is called a flexor.
    • A muscle that straightens a joint is called an extensor.


  • Central Nervous System:

    Invertebrate nervous systems:   Most invertebrates have nervous systems derived from the ladder-like arrangement in flatworms.
    • Cnidaria have a nerve net of interconnected neurons with no center.
    • Flatworms have two long chains of ganglia in a ladder-like arrangement;
      the largest ganglia, near the eyes, form the beginnings of a "brain."
    • Most other invertebrates have modifications of this ladder-like pattern; a major nerve cord runs along the ventral midline, splits to form an esophageal ring, and reunites above the mouth to form a cerebral ganglion or brain.
    Embryonic vertebrate brains form as three major divisions:
    • Forebrain (prosencephalon), primitively devoted to smell
    • Midbrain (mesencephalon), primitively concerned with vision
    • Hindbrain, dealing with sound and vibrations
    Adult vertebrate brains: Organized into five regions:
    • Telencephalon: paired parts of the forebrain, including olfactory bulbs, olfactory lobes, and cerebral hemispheres, which enlarge greatly in mammals and take over many added functions.   The size and complexity of the cerebral hemispheres are a crude measure of intelligence.
    • Diencephalon: unpaired, second portion of the forebrain, including the pineal body (epiphysis); tela choroidea (thin roof); thalamus (controls many emotions); hypothalamus (controls appetite and body temperature); and part of the pituitary gland.
    • Mesencephalon: midbrain, including corpora quadrigemini
    • Metencephalon: includes cerebellum and pons
    • Myelencephalon: medulla, continuing into the spinal cord
    Brain ventricles: cavities containing cerebrospinal fluid
    Spinal cord:
          White matter: myelinated tracts
          Gray matter: unmyelinated motor and sensory columns

    Spinal reflex pathway:
    • Sensory neuron runs from a receptor cell in skin to cell body in dorsal root ganglion, then into somatic sensory column of spinal cord.
    • Association neuron connects somatic sensory column to somatic motor column in spinal cord.
    • Motor neuron runs from somatic motor column out ventral root to a to a voluntary muscle or other effector cell.

  • Gas Exchange:
    Flatworms and other flattened animals need no special organs for gas exchange because no cell is very far from a body surface.
    More complex animals use lungs, gills, or tracheal tubes.

  • Gill systems:   In fishes and many other aquatic animals, thin-walled arteries run through gills with direction of blood flow usually opposite to flow of water (counter-current exchange). Oxygen diffuses into these arteries; CO2 diffuses into surrounding water.
  • Insect tracheal systems: Air diffuses through numerous branched tubes (tracheae). Rhythmic muscular contractions force air in and out when flying, but air movement is passive most of the time.
  • Lung-based gas exchange in land vertebrates:
    • Nostrils take air into nasal cavity, then into pharynx. Floor of pharynx opens behind mouth into larynx (voice-box); entrance to larynx is guarded by epiglottis.
    • The trachea, bronchi, and bronchioles form tree-like branchings within each lung.
    • The lungs have air sacs lined with box-like alveoli.
    • Air exchange: In inhalation (inspiration), diaphragm contracts and moves downward while intercostal muscles raise rib cage.     In exhalation (expiration), muscles relax, rib cage falls, diaphragm springs upward.
    • Gas exchange in alveoli: Oxygen enters capillaries of lung through thin walls; CO2 leaves capillaries and diffuses into air sac.
    • Gas exchange within capillary blood: In lung alveoli, oxygen enters red blood cells, combines with hemoglobin, and is transported as HbO2 (oxyhemoglobin); bicarbonate ions enter blood cells and are split into water and CO2. The reverse occurs in body tissues: oxyhemoglobin breaks down to release oxygen; CO2 and water combine to form bicarbonate ions (HCO3–).

  • Internal Transport (circulation):
    Very small or very thin organisms need no special system for internal transport. Many invertebrates have an open system, with blood vessels opening into a general circulatory cavity or hemocoel. Vertebrates have a closed circulatory system: their hearts pump blood from atrium to ventricle and then through the major arteries; veins return blood to the heart.

    Simple forms of transport:
    • Cytoplasmic streaming (cyclosis): Cytoplasm in all eucaryotic cells continually flows and changes direction.
    • Diffusion: Passive transport in all organisms, effective only at distances of a few cells. This may suffice for organisms in which each part is only a few cells away from a body surface, but larger animals need circulatory systems.
    Open circulatory systems: Systems in which a body cavity or hemocoel contains most of the circulating fluid, as in insects.
    • The pumping action of a heart drives fluid forward through an aorta, then through a series of arteries. No veins exist; used blood seeps into sinuses that drain into the hemocoel.
    Closed circulatory systems: Systems in which blood is everywhere contained in vessels, as in all vertebrates.
    • The heart may have 2 to 4 chambers. The heartbeat originates from a pacemaker at the sinoatrial node. Highest pressure, at maximum contraction, is called systole; lowest pressure is called diastole.
    • In mammals, the right atrium pumps oxygen-poor blood from the body's tissues into the right ventricle, which pumps it through the pulmonary arteries into the lungs. The left atrium meanwhile pumps oxygen-rich blood from the lungs into the left ventricle, which pumps it through the aorta for distribution throughout the body.
    • Arteries carry blood from the heart to the body's tissues.
    • Veins return the blood from the body's tissues back to the heart.
      Valves in veins prevent the blood from flowing backward.
    • Vertebrate blood is always red because of the oxygen-carrying pigment hemoglobin, carried in red blood cells (erythrocytes).


  • Osmoregulation and Excretion:
    Freshwater organisms tend to gain water across membrane surfaces and must actively get rid of it. Land and marine organisms tend to lose water; they must retain water and excrete salt. Vertebrate kidneys filter the blood first, then retrieve (resorb) useful molecules.
    • Osmotic pressure measures the level of dissolved ions in solution.
    • Hypotonic solutions (low osmotic pressure, few dissolved ions):   Cells swell (or may burst) because water diffuses in. Freshwater organisms always gain water from hypotonic surroundings; they void lots of dilute urine and may actively take up some ions.
    • Hypertonic solutions (high osmotic pressure, many ions):   water diffuses out; cells shrink. Marine and land animals lose water across membranes; they excrete concentrated urine or salt-rich fluids.
    • Isotonic solutions: Cells have the same concentration of dissolved ions. Water enters and leaves at the same rate, so cells stay the same size.
    • Simple excretory systems: Some freshwater protists pump water out by contractile vacuoles. Many small aquatic animals allow wastes to diffuse out. Flatworms have single-celled excretory tubules called flame cells.
    • Nephridial systems: Tubules (nephridia) drain coelomic fluid from the body cavity and exchange ions with small blood vessels nearby.
    • Vertebrate kidneys:   Cortex (outer layer) contains mostly glomeruli and convoluted tubules; medulla (inner layer) is made of several medullary pyramids, which contain Henle's loops.
    • Kidney tubules:   Blood plasma is filtered from a series of thin-walled blood vessels (the glomerulus) into Bowman's capsule. In the proximal convoluted tubule, the blood resorbs glucose and some ions. In mammals, Henle's loop resorbs water. In the distal convoluted tubule, more ions return to the blood. Collecting tubules finally concentrate the urine and drain into the renal pelvis, which drains into the ureter.
    • Nitrogen wastes: In mammals, the principal nitrogen waste is urea. Reptiles and insects excrete uric acid instead. Fishes and many other aquatic animals usually excrete ammonium salts.
    • Other organs of excretion: Lungs and gills get rid of CO2. Animals excrete salt and nitrogen wastes through the skin.




  • Deuterostome taxa and their characteristics:
    • Deuterostomia:   a group of phyla characterized by radial, indeterminate cleavage in early embryos and by an embryonic blastopore that becomes the tail end of the adult.
    • Echinodermata:   deuterostome animals with a water-vascular system, usually developing 5-fold radial symmetry as adults.
      Sessile (attached) echinoderms (Homalozoa and Crinozoa) include crinoids (sea lilies) and various extinct groups (blastoids, cystoids, carpoids, etc.). Many grow on stalks attached to the bottom. Body cup-shaped, open toward the top, with a mouth in the center of the top surface. Arm-like rays, in multiples of five, grow out and upward from the margins of the mouth. Each ray has a ciliated groove that traps food particles and brings them to the mouth. Today, only a few crinoids remain; other attached echinoderms are extinct.
      Free-moving echinoderms (Echinozoa and Asterozoa) are mostly bottom-feeding scavengers and predators that attack other invertebrates. The mouth, on the lower surface, faces downward. Branches of the water-vascular system may form foot-like podia, used in locomotion.
      • Asterozoa: Body star-shaped, with protruding arms. Includes starfishes and brittle stars.
      • Echinozoa: Body globe-shaped, with no protruding arms. Includes sea cucumbers, sea urchins, and sand dollars.
    • Hemichordata: Acorn worms and their relatives, all filter feeders, some using gill slits, others using tentacle-like feeding structures. Related to Chordata, but now usually treated as a separate phylum.
    • Chordata:   deuterostome animals with a notochord, a series of gill slits, and a dorsal, hollow nerve cord; these traits may occur in larval stages, not always in adults.
      • Urochordata (tunicates or "sea squirts"): An actively swimming larva with well-developed notochord and nerve cord undergoes metamorphosis into a filter-feeding adult. The adult usually passes large amounts of water through a large gill basket.
      • Cephalochordata (sea lancets or amphioxus): Small, thin animals that filter feed by passing water through many gill slits. A notochord extends the entire length of the animal, including the head.
      • Vertebrata (vertebrates): Animals with a vertebral column (backbone) that functionally replaces the notochord in adults, and a braincase that encloses and protects the brain. Examples: fishes, amphibians, reptiles, birds, and mammals.
        • "Fishes": general term for aquatic vertebrates that have fins and gills throughout their adult lives, and swimming by side-to-side undulations of the body; a very heterogeneous assemblage of 4 distinct classes as follows:
        • Class Agnatha: Jawless fishes, often with a filter-feeding larval stage. Modern forms (cyclostomes) include parasitic lampreys and hagfishes.
        • Class Placodermi: An extinct group in which jaws and paired fins first evolved.
        • Class Chondrichthyes: Cartilaginous fishes, including sharks, skates, and rays.
        • Class Osteichthyes: Bony fishes, including the vast majority of fishes. Scales and internal skeleton typically bony. One great subgroup (Actinopterygii) has fins with ray-like supports but no internal muscles; a much smaller subgroup (Sarcopterygii) has fleshy, lobe-like fins with internal muscles.
        • Class Amphibia: Eggs are laid in contact with fresh water, then fertilized externally. Larvae ("tadpoles") breathe with gills, then undergo metamorphosis into an adult, usually with lungs and legs. Living species always have slippery, moist skin. Examples: salamanders, newts, frogs, toads, and extinct labyrinthodonts.
        • Class Reptilia (Sauropsida): Reptiles lay a shell-covered amniote egg that must be laid on land, or else hatched inside the female's body. Reptiles have a dry, tough (leathery or scaly) skin and Internal fertilization; legs are generally stronger than in amphibians. Examples: turtles, snakes, lizards, dinosaurs, and crocodiles.
        • Birds are vertebrates evolved from dinosaurs and adapted for flight; adaptations include feathers, wings, warm-blooded metabolism, hollow bones, and loss of teeth and tail bones.
        • Class Mammalia: Vertebrates covered with hair or fur (occasionally blubber), with high metabolic rates and constantly warm body temperatures (homeothermy). Sweat glands and sebaceous glands in skin. Young mammals are nursed by their mothers by milk secreted by mammary glands; frequent parental care. Normal standing posture keeps the body elevated from the ground. Three tiny ossicles (malleus, incus, stapes) transmit sounds in middle ear. Four-chambered heart has complete separation of oxygen-rich and oxygen-poor blood. Only one bone, the dentary, makes up the lower jaw on each side. A muscular diaphragm is responsible for most breathing movements. A bony hard palate separates nasal cavity from oral cavity, allowing breathing and chewing at the same time. Teeth vary in shape with their position in the mouth and are restricted to only two waves of growth and replacement instead of many. Brain and braincase larger than in reptiles.
          • Nearly 40 orders (half of them extinct), including:
          • Monotremata: egg-laying mammals (platypus and echidna)
          • Marsupialia: opossums, kangaroos, koalas, and other pouched mammals
          • Rodentia: squirrels, beavers, rats, mice, and others with large gnawing incisor teeth.
          • Lagomorpha: rabbits
          • Carnivora: dogs, wolves, cats, bears, weasels, raccoons, seals, etc.
          • Cetacea: whales (including dolphins and porpoises)
          • Artiodactyla: cattle, deer, pigs, and other hoofed mammals with even toes
          • Perissodactyla: horses, rhinoceroses, and other hoofed mammals with odd toes
          • Proboscidea: elephants
          • Chiroptera: bats
          • Primates: the mammalian order to which we belong, including monkeys, apes, humans, lemurs, tarsiers, etc.
            Most primate characteristics arose as arboreal adaptations (adaptations to life in trees):
            • Arboreal locomotion
            • Grasping hands and feet (which wrap around branches)
            • Opposable thumb and/or big toe (wrap around in opposite direction from other digits)
            • Increased freedom of rotation in forearm
            • Increased reliance on vision (including color) and less on smell
            • Binocular, stereoscoptic vision (in depth)
            • Expanded visual centers in brain; more folds in brain surface
            • Visual inspection and manipulation of objects
            • Increased intelligence
            • Greater reliance on learned behavior; juvenile inexperience
            • Longer and more intense parental care
            • Uteri fuse into uterus simplex
            Types of primates include:
            • Plesiadapoidea or Paromomyiformes: Extinct, archaic primates.
            • Lemuroidea or Strepsirhini: Lemurs, lorises, and galagos.
            • Tarsioidea: Tarsius and its extinct relatives.
            • Platyrrhina: New World monkeys and marmosets, with 3 premolars in each jaw, flat noses, and strong tails that aid in locomotion.
            • Catarrhina: The group to which we belong, including old World monkeys, apes (gibbons, orangutan, gorilla, chimpanzees) and humans, with only two premolars in each jaw, protruding noses (nostrils opening downward), and reduced tails, native to Africa, Asia, and Europe.
            Humans walk upright. The many consequences of this include tool use, speech, and anatomical changes such as an S-shaped vertebral column (with a lumbar curve) and a more rounded cranium from which the spinal cord exits at the bottom. Humans are distinguished from apes by the following traits:
            • Upright, bipedal locomotion (walking, running)
            • Larger and more rounded braincase
            • Spinal column exits (through foramen magnum) at bottom, not rear, of the skull
            • Reduced spines on neck vertebrae
            • Spinal column gently S-shaped, with lumbar curve (concave to rear along lower back)
            • Pelvis wider; iliac crests expanded
            • Gluteus maximus enlarged and rotated to the rear, pulling leg to the rear instead of sideways
            • Canine teeth reduced (tools are now major weapons)
            • Lower jaw symphysis strengthened by chin
            • Tooth rows rounded instead of parallel
            • Habitual use of tools (hands free to hold them)
            • Habitual use of language
            Origin of Hominidae: Approximately 5-6 million years ago when upright posture was attained. Human footprints at Laetoli, Kenya, are 4.1 million years old.
            Evolutionary "dead ends": A number of hominid fossils are now considered to be evolutionary "dead ends," not ancestral to modern humans. These include Sahelanthropus, Ororrin, Kenyapithecus, Ardipithecus, and the large or "robust" Australopithecus robustus and A. boisei.
            Australopithecus: The best-known early hominids, from South Africa and East Africa. Certain early species (Australopithecus anamensis, A. afarensis) may have been ancestral to Homo, but later species were not. One nearly complete skeleton of A. afarensis, nicknamed "Lucy," was only about 4 feet tall and walked upright.
            Homo habilis: An East African contemporary of Australopithecus, from about 4 to 1.5 million years ago. Body size about 4 feet tall. Perhaps responsible for early stone tools.
            Homo erectus: Lived in the middle Pleistocene, after the extinction of Australopithecus. Fossils known from Europe, Africa, Asia. In a cave near Beijing, China, heat-fractured rocks show that fire was used.
            Homo sapiens: First appeared in the late part of the Ice Age. Taller skull than earlier species. Used more advanced tools. Invented agriculture around 8,000 years ago.


  • Evolutionary Advances among Deuterostomes:
    • Notochord, segmental muscles, dorsal hollow nerve cord, and gill slits
                  Know how each of these features functions.
    • Emergence onto land
                  Sarcopterygian fish already had lungs and choanae.
                  Early amphibians transformed fleshy fins into walking legs that could be used on land.
    • Amniote (cleidoic) eggs
                  These eggs were laid on land instead of in the water.
                  Know the functions of the shell, chorion, amnion, and allantois. (See vocabulary below.)
    • Homeothermy; parental care and feeding
                  Maintenance of constantly warm body temperature permitted more vigorous activity (flying, running);
                  it evolved independently in several lineages.
                  Parental care and feeding of the young also evolved multiple times. Mammals nourish their young with milk.




  • Animal Behavior:
    • Simple behaviors— can be described by a single imperative.   Tropisms and taxes directed toward a stimulus are called positive; those directed away from the stimulus are called negative.
      • Tropisms are growth or turning movements in plants or sessile animals. Tropisms include:
        • Phototropism: growth or turning toward light (positive phototropism) or away from light (negative phototropism).
        • Geotropism (gravitropism): growth toward or away from the earth's center.
        • Chemotropism: growth toward or away from a chemical; special types include halotropism for salt or hydrotropism for water.
        • Anemotropism: growth toward or away from a source of wind.
        • Thigmotropism: growth toward or away from something touched.
      • Taxes: Oriented locomotor behaviors.
        • Phototaxis: motion toward or away from light.
        • Geotaxis: motion toward or away from the earth's center.
        • Chemotaxis: motion toward or away from a chemical; special types include halotaxis for salt or hydrotaxis for water.
        • Anemotaxis: locomotion upwind (positive) or downwind (negative).
        • Rheotaxis: swimming upstream (positive) or downstream (negative).
      • Kineses: Non-oriented locomotion, with no particular direction.
        • Photokinesis: locomotion in response to light.
        • Chemokinesis: locomotion in response to chemicals.
        • Thigmokinesis: locomotion in response to touch.
    • Instincts: Complex, innate behaviors (following inborn instructions).
      • "Complex" means that several acts need to be done in proper succession.
      • "Innate" means inborn or genetically programmed. A standard test is whether animals raised alone from birth can perform the behavior correctly.
      • Usually stereotyped, meaning that the behavior does not vary from one occasion to another or one performer to the next (good for courtship and species-recognition behavior).
      • Advantage: No time or effort is wasted in learning or in making mistakes; behavior is correct the first time.
      • Disadvantages: Cannot be modified to suit circumstances.
      • Examples: Most aggressive or submissive postures and movements; courtship and mate-attracting behaviors (songs, etc.), nest-building behaviors in many species, web-weaving in spiders, territoriality.
    • Learned behaviors: behavior that improves with practice.
      • More variable than instinct, an advantage in interactions with the local environment, but a disadvantage in mate recognition or courtship.
      • Advantages: Can be varied to suit locality or circumstance; can become more complex than instincts.
      • Disadvantages: Learning (and mistakes) must take place first; youthful inexperience is a price. The amount of possible learning is limited by neural complexity.
      • Types of learned behavior include:
        • Imprinted behavior: Behavior learned very early in life.
        • Conditioned learning: Any behavior with a pleasant result will be reinforced and repeated; behavior with an unpleasant result is discouraged. If the outcome depends on pre-existing stimuli, subject will learn to discriminate on the basis of those stimuli.
        • "Insight" or "rational" learning (mostly in mammals): Solution occurs all at once, in a "flash of insight" (or "aha!"). Much learning occurs in play and exploratory behavior and by imitation.
        • Symbolism and language: Primates can be taught that a stimulus has an arbitrary meaning (if it stands for something else). The highest form of symbolism is language.
      • Learning and intelligence: Intelligence is a capacity for learning increasingly complex behaviors. It correlates with brain size only if species of similar size are compared. Mammals are generally the most intelligent animals. Symbolic behavior and language are keys to human intelligence.




    • ADDITIONAL VOCABULARY:
              Deuterostome:   Animals whose embryos exhibit radial, indeterminate cleavage and whose blastopore
                  is located near the future hind end, with the mouth forming secondarily at the opposite (front) end.
              Radial cleavage:   Embryonic cell division producing, in the 3rd cleavage, four smaller cells directly
                  atop four larger cells.
              Spiral cleavage:   Asymmetrical cell division in the 3rd embryonic cleavage, producing four smaller
                  cells staggered between the tops of four larger cells.
              Indeterminate cleavage:   Cleavage in which embryonic fate is determined late, so that cells experimentally
                  isolated from early embryos are still able to form structures both right and left, front and rear, etc.
              Notochord:   A stiff, flexible rod, forming the body axis, and allowing the body to bend but not shorten
                  when muscles contract; in embryos, it induces the nervous system to form above it.
              Gill slits:   Openings from pharynx to either side, just behind mouth.
              Choanae:   Nasal passages, connecting the external nostrils with the internal nostrils.
              Chorion:   Embryonic membrane just inside the shell.
              Amnion:   Encloses the embryo in its own protective watery bag.
              Allantois:   Serves as a lung-like respiratory organ for the embryo.
              Placenta:   Intimate branching of embryonic blood vessels into the wall of the mother's uterus, nourishing
                  the baby in utero, an adaptation present in most mammals (but not monotremes or marsupials).
              ** Also the animal taxa and other topics outlined above. **  

    • MORE DETAILS are contained in the following outlines:
      29.Deuterostomes     30.Fishes     32.Amniotes     33.Mammals     31.AnimalBehavior


    • THIS GUIDE will continue to be revised. It is still tentative.

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    Index             Syllabus
    rev. Nov. 2015