Biology 193- Exam 3

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What are the Characteristics/Advantages of Anthropodas?

• Hard Exoskeleton (cuticle)

  • Protects the animals without loss of mobility and reduces desiccation in terrestrial species

  • Fusions of body segments (tagmatization)

    • Each fused part called a tagmata

    • Allows for specialization of certain body parts

  • Development of specialized joint appendages

    • Usually each tagma has a pair of jointed appendages

    • Appendages can be specialized for certain functions (moving, feeding, sensory)

  • Development of specialized respiratory systems

    • In water: most have gills

    • On land: most have a respiratory system that consists of tubes that deliver air directly to cells (tracheal system)

    • Allow for a higher metabolic rate and level of activity

  • Development of specialized sensory systems

    • Possess a variety of sensory organs

  • Development of Complex Behaviors

    • Have complex innate behaviors and some are capable of learning

    • Some even show communication and cooperation

  • Metamorphosis

    • Most have a larval stage that differs morphologically and behaviorally from the adult

    • Reduces competition between larvae and adults by allowing them to occupy different ecological niches

General Characteristics of Arthropoda

• Triploblastic

• Bilaterally symmetrical

• Coelomates

What is Ecdysis?

• When an organism must ‘molt’ its shell to grow

What is the Exoskeleton/Cuticle of Arthropoda made of?

• Made of protein and chitin

What is Tagmatization and What Animal Groups Show This. ?

• The fusion of body segments

• Arthropods show tagmatization

What are Myriapoda

• A phyla of Arthropoda

• Includes millipedes and centipedes

• All terrestrial

• Have a pair of antennae and 3 pairs of feeding appendages (including jaw like madibles)

Millipede Characteristics

• Don’t have 100 legs

• Each trunk segment formed from 2 fused segments

• Have 2 pairs of legs

• Herbivores

Centipede Characteristics

• Don’t have 100 legs

• Each trunk segment has 1 pair of legs

• Carnivorous

What are Cheliceriformes?

• Phyla of Arthropoda

• Includes spiders, scorpions, ticks, mites, horseshoe crabs

• Named for their claw like feeding appendages (chelicerae)

• Mainly terrestrial, a few marine species

What are Crustaceans?

• A phyla of Arthropoda

• Mainly aquatic (freshwater and marine) but some terrestrial

• Many have highly specialized appendages

  • Crustaceans have 2 pair of antennae (only group)

  • All have modified mouthparts, and many have specialized walking legs and/or swimming appendages

What are Insects?

• A phyla of Arthropoda

• More species that all other groups combined

• Very abundant in all habitats except the marine environment

• Most have the advantage of flight

• May have one or two pairs od wings

  • Wings are extensions of the cuticle (not true appendages)

• Repro is usually sexual with internal fertilization

  • Sperm is either directly deposited vaginally or places as a packet outside the female and she picks it up

  • Sperm is stored inside the female in a structure called the spermatheca

Metamorphosis in Insects?

• Growing non-reproducing larva or nymph with no wings → non-growing reproducing adult and usually have wings

General Characteristics of Echinodermata

• Includes seas stars, brittle stars, sea urchins, sea cucumbers, sand dollars, and feather stars

• Deuterostomes

• Many radially symmetrical as adults (but have bilaterally symmetrical larvae)

• Triploblastic

• Coelomates

• Entirely aquatic

How is the Water Vascular System of Echinodermata Used for Locomotion?

• Urchins, sea stars and cucumbers use tube feet to move

• Hydrostatic skeleton of water vascular system can be used to independently move individual tube feet

How is the Water Vascular System of Echinodermata Used for Feeding?

• Use their water system to manipulate tube feet to capture food

• Manipulate the water to bring food to mouth

• Starfish are carnivorous, specializing on molluscs

• Brittlestar may be carnivorous or filter feeders

• Urchins graze on algae

• Sea cucumbers filter feed

How is the Water Vascular System of Echinodermata Used for Gas Exchange?

• Water enters through the Madreporite and circulates through canals and tube feet

• Spine and gills on tube feet

What are the 4 Characteristics all Chordates Share?

• Notochord

• Dorsal hollow nerve cord

• Pharyngeal slits

• Muscular, postanal tail

What is the Notochord?

• A flexible rod-like structure

• Made of large fluid filled cells encased in a still fibrous tissue

• Extends the length of the body

• An axis for muscle attachment

• In all jawed vertebrates, it is replaced by a series of cartilaginous or bony vertebrate

What is the Dorsal Hollow Nerve Cord?

• A single hollow tube-like nerve cord

• Dorsal to the alimentary canal and the notochord

• In vertebrates, the anterior end becomes enlarged to form the brain

• Develops from a plate of ectoderm

• In some animals develops into the central nervous system consisting of the brain and spinal cord

What are Pharyngeal Slits?

• Perforated slit-like opening that connect the pharyngeal opening and the outside

• Formed by alternating pharyngeal grooves and pouches

• In aquatic chordates, they become the gills

• In tetrapod (4 limbed) vertebrates, they become parts of the throat and ear cavity

What is the Muscular Post-anal Tail?

• Located posterior to the anus

• Associated with somatic musculature (segmented and anchored to the notochord)

• Provides motility in the aquatic environment

• Lost during development of many chordates

What are Cephalochordata?

• The Lancelets (Amphixous)

• 26 species, up to 5 cm in length, marine

• Have all 4 chordate characteristics throughout their lifecycle

• Use cilia around head to move water through pharyngeal slits to feed

• Muscles are formed in serial segments of mesoderm called somites

What are Urochordata?

• Sub-phyla of Chordata

  • Includes tunicates, ascidians, and sea squirts

  • All marine, most sessile as adults

  • Exhibit all four chordate traits during a brief larval stage

  • Had genes associated with the vertebrate heart and thyroid gland

Are Lancelets or Tunicates More Morphologically Similar to the Average Chordate?

• The Lancelet is more similar to the average Chordate

What are Craniates?

• Chordates with a head (usually consisting of a brain at the anterior end of the dorsal nerve cord, eyes and other sensory organs, and a skull)

Hox Genes Role in Evolution of Craniates?

• After Lancelets and Tunicates there was a duplication of chordate HOX genes

  • Promoted skull and sensory organ development

  • Head allows complex movement and predation

What is the Neural Crest?

• A feature unique to craniates

• Disperse through the body and give rise to a variety of specialized structures including:

  • Teeth

  • Some of the bones and cartilage of the skull

  • The dermis (inner layer of skin)

  • Several types of neurons

  • Sensory cells associated with the eyes

Hagfishes?

• 43 species, entirely marine

• Feed on dead or dying fish, whales and crustaceans (anything!)

• Retain a notochord as adults

• Have a cartilage skull but NO jaws or vertebrate

Lampreys (Petromyzontida)?

• 84 species, the oldest living vertebrate lineage, freshwater and marine

• Fibrous and cartilaginous ‘skeleton’ surrounds the notochord and nerve cord, with paired cartilaginous projections related to vertebrate extending dorsally

• No scales; no paired appendages, adults are jawless with a sucker-like oral disk containing well developed teeth

• Adults are parasitic on other fish

• Filter feeding in lamprey ‘ammocoete’ larvae

Origin of Bones?

• Vertebrate skeleton evolved initially as a structure made of un-mineralized cartilage (lamprey)

  • Mineralization began after lampreys diverged from other vertebrates

• First mineralized structures included mineralized mouthparts of conodonts

• Later some fish develops armored plates for protection

• Skull and endoskeleton mineralized later

Advantages of developing bone

• Increased mobility

• Increased diet/feeding

• Increased protection

Gnathostomes- the jawed vertebrates

• Mineralized hinged haws and teeth

  • Enable firm grasping and slicing of food

• Evolved from pharyngeal slit skeletal supports

• Gill slits remain major site of gas exchange

Chondricthyes General Characteristics

• 850 species

• Bony skeleton replaced with flexible cartilage

• No swim bladder

• 5-7 exposed gill slits

• Have well developed sensory organs

Buoyancy Control in Chondricthyes

• Cartilaginous skeleton is lighter than bone

• Have very large fatty livers to help with buoyancy

• Large pectoral fins act as ‘wings’ to aid in level swimming

Sensory Structures of Chondricthyes

• Lateral line - can detect pressure differences in the water

• ‘Ampullae of Lorenzini’ - can detect electrical signals

Chondricthyes Reproduction

• Shared cloaca∫ for reproduction and waste excretion

• Male uses claspers to fertilize female internally

• Various modes of reproduction:

  • Oviparous: eggs hatch outside mother

  • Ovoviviparous: embryo fed by yolk in uterus

  • Viviparous: embryo fed by placenta in uterus

What are Osteichthyes (the ‘bony’ fishes)?

• Phyla of Chordates

• More than 2500 species

• Mostly bony skeleton

• Gill supported by bony gill arches and covered by an operculum

• Group technically includes all bony fish an tetrapods

Characteristics of Actinopterygii (ray-finned fishes)?

• Flexible rays support fins

• Operculum flap protects and ventilates gills

• Skin contains bony scales and lateral lines pits

• Air-filled swim bladder regulates buoyancy

• Most are oviparous with external fertilization

  • Also possible hermaphroditic cloning and birth to ‘live’ babies

What is a Swim Bladder?

(used by many bony fishes)

• Can be deflated and inflated depending on depth (and therefore pressure) the fish is swimming at

• Gasses are taken up by gills and are transferred to the blood then used to inflate the swim bladder

Characteristics of Sarcopterygii (lobe-finned fishes)?

• Include coelacanth, lungfish, and tetrapod lineages

• Thick muscles of pectoral and pelvic fins surround rod-shaped bones

Why are Coelacanths so Special?

• They were though to be extinct until 1938

• Has lobed fine

• Has a hinged skull

• Important evolutionary species

Characteristics of the Lungfishes- Dipnoi

• Have a true long

• Can go aestivate (dormant) for several months during the dry season by burrowing themselves into the mud and secreting a leathery cocoon around themselves

What are Tetrapods and Adaptations?

• They are gnathostomes that have limbs

• Four limbs with digits

• A neck, which allows separate movement of the head

• Fusion of the pelvic girdle to the backbone (ribs)

• The absence of gills (except some aquatic species)

• Ears for detecting airborne sounds

What is a Fishapod?

• Contains fins, gills, lungs, and scales

• Has a neck and ribs to breathe air and support it’s body weight

• Has fins with the bone pattern of a tetrapod limb

  • Humerus, Ulna, “Wrist”, Elbow, Radius

What are the Three Main Orders of Amphibians?

• Urodela

  • The salamanders

  • Have tails

• Anura

  • The frogs and toads

  • Lack tails

• Apoda

  • The caecilians

  • Lack legs

Characteristics of Amphibians?

• Both ways of life

• Aquatic larva/terrestrial adult (think frogs)

• Reproduction

  • Fertilization is typically external, with eggs deposited in water or other moist environments

  • Some species show parental care, holding eggs in their mouth, stomach or in pouches on their back

What is Paedomorphosis?

• Retention of larval features when sexually mature (common in some aquatic salamanders)

What Characteristics do Amphibians, Reptiles, and Mammals Share?

• Paired limbs

• Vertebrates

• similar skeletal structures

What are Amniotes?

• Tetrapods with a terrestrially adapted egg

• Includes the reptiles (including birds) and mammals

Parts of the Amniotic Egg?

Allowed amniotes to occupy a wider range of terrestrial habitats as it is resistant to desiccation

• The amnion encloses a compartment of fluid that bathes the embryo and acts like a hydraulic shock absorber

• The chorion (and the allantois) exchange gases between the embryo and the air. Oxygen and carbon dioxide freely diffuse through the egg shell

• The allantois is also a disposal sac for certain metabolic wastes

• The yolk sac contains ‘yolk’ a nutrient rich liquid that is used by the embryo for energetic needs, has blood vessels that deliver nutrients to the embryo

Mammals have evolved to develop the fertilized egg within the mother’s amnion, therefore not requiring the egg-shell to resist desiccation

Reptiles?

• Includes the tuataras, lizards, snakes, turtles, crocodilians, and birds

  • Tuataras include only two extant species

  • Squamates include the lizards and snakes (~7900 species)

  • Snakes descended from lizards and have lost their legs but some still retain vestigial pelvic and limb bones

  • Turtles have a box like shell made of upper and lower shields that are fused to the vertebrate, clavicle and ribs

  • Alligators and crocodiles (crocodilians) confined to warm regions

• All (except birds) have scales that help the animals resist desiccation and protect from abrasions

• Most lay shelled eggs on lans

• Most are exothermic, but birds are endothermic

Origin of Birds?

• ~10,000 species

• In the same evolutionary lineage as crocodilians and extinct dinosaurs

• Probably descended from small theropods (a group of carnivorous dinosaurs)

• Early feather may have evolved for insulation, camouflage, or courtship display

• Most features of their anatomy have been modified for flight

  • Advantage for hunting, scavenging, escaping predators BUT requires a lot of energy, acute vision, and fine muscle control

Adaptations for Flight in Birds?

• Honeycomb air-filled bones

• Lack of a urinary bladder

• Females have only one ovary

• Small gonads

• Loss of teeth

• Large pectoral muscles anchored to keel on the sternum

  • Some flightless birds have underdeveloped pectoral muscles and lack a sternal keel

  • Some are ‘flightless’ but have retained large pectoral muscles for other forms of flight

Endothermic (thermoregulators) vs. Ectotherms (thermoconformers)

• Endotherms (thermoregulators): regulate body temp (mammals, birds and some fishes)

• Ectotherms (thermoconformers): allows body temp to change with environment

Conformers vs. Regulators vs. Regional Heterothermy

• Conformers: allow internal conditions to change with external conditions

• Regulators: maintain relatively constant internal conditions regardless of external conditions

• Regional heterothermy: some fishes (tuna and sharks) are able to warm parts of their body using counter-current exchange. They produce heat with their muscles and that heat is conserved in the core of the body

Characteristics of Mammals?

• Amniotes with hair that produce milk

• Derived characteristics

  • Mammary glands, which produce milk

  • Hair

  • A high metabolic rate, due to endothermy

  • A larger brain that other vertebrates of equal size

  • Differentiated teeth

What are Synapsids?

• Have a temporal fenestra, a hole behind the eye socket on each side of the skull

• Jaw muscles pass through fenestra to be anchored to the temple

  • Mammals have also incorporated two bones found in the jaw of reptiles into bones of the inner ear

  • Eardrums allow sound to be pushed through and sent to the nervous system

What are the 3 Lineages of Mammals?

• Monotremes

• Marsupials

• Eutherians

Monotremes?

• 5 species

• A small group of egg-laying mammals (echidnas and platypus), produce milk through skin

Marsupials?

• 324 species

• Include opossums, kangaroos, and koalas

• Embryo develops in a placenta in the mother’s uterus

• A marsupial is born very early in its development

• It completes its embryonic development while nursing in a maternal pouch called a marsupium

Eutherians?

• Placental mammals, ~5,010 species

• Compared with marsupials, eutherians have a more complex placenta

• Young eutherians complete their embryonic development within a uterus, joined to the mother by the placenta

Primates?

• Includes lemurs, tarsiers, monkeys, and apes (humans included)

• Most have:

  • Hands and feet adapted for grasping, and flat nails

  • A large brain and short jaws

  • Forward-looking eyes close together on the face, providing depth perception

  • Complex social behavior and parental care

  • A fully opposable thumb (in monkeys and apes)

Humans?

• A number of characters distinguish humans from other apes:

  • Upright posture and bipedal locomotion

  • Larger brains capable of language, symbolic though, artistic expression, the manufacture and use of complex tools

  • Reduced jawbones and jaw muscles

  • Shorter digestive tract

  • Originated in Africa about 6-7 million years ago

  • Early hominins show evidence of small brains and increasing bipedalism

Two Common Misconceptions of Humans?

• 1. Early hominins were chimps

  • Correction: Hominins and chimps shared a common ancestor

• 2. Human evolution is like a ladder leading to Homo Sapiens

  • Correction: Hominin evolution included many branches or coexisting species, though only humans survive today

Purpose of Circulatory Systems and Why Some Animals Don’t Have Them?

• Used for maintaining homeostasis

• Used for transporting oxygen, nutrients, and other substances throughout cells

• Remove waste products and carbon dioxide

• Some animals have simple and thin enough skin and systems that diffusion is adequate

Limitations of Diffusion?

• Limited by surface are to volume ratio

• Distance of transport

• Thickness and permeability of the plasma membrane

• More complex systems

What is Bulk Flow?

• How large animals move fluid, blood, and gases through their body

• Movement of fluid molecules as a group

• Requires input of energy

• Transport can occur over greater distance

What are the 3 Main Components of the Circulatory System?

• Blood vessels

• Blood

• Heart

Closed vs. Open Circulatory Systems?

• Open

  • Hemolymph

  • Flows freely through open spaces or sinuses in the body cavity

  • Bathes organs

  • Blood pressure is generally low, slower circulation

• Closed

  • Keeps blood contained in a network of blood vessels

    • arteries, veins, and capillaries

  • Ensures a continuous and direct flow

  • Blood pressure is typically higher, allowing for faster and more efficient circulation

Circulatory Systems in Different Species?

• Fish: closed

• Amphibians: closed

• Birds: closed

• Reptiles: closed

• Mammals: closed

What are Osmoregulators"?

• Species that can maintain their blood salinity (osmolarity) different from the environment

• Mammals

  • most terrestrial vertebrates (like humans), some marine animals, and freshwater fish

• Birds

What are Oscmoconformers?

• Regulate the types of ions (salts) they put in the blood different from the seawater (also ionregulators)

• Most aquatic invertebrates

  • starfish, mussels, crabs, lobsters, jellyfish, sea squirts (ascidians), and scallops

• Hagfish

What are Ionconformers?

• organisms that maintain a similar internal ionic composition to their external environment. They rely on the ionic composition of their surrounding environment, like seawater, for crucial biological functions.

What are Ionregulators?

• organisms that actively control the concentrations of ions and water in their body fluids, keeping them separate from the surrounding environment