Bio Exam 3

Describe the defining characteristics of animals

• eukaryotes

• multicellular heterotrophs

• have cells that lack cell walls

Describe the animal life cycle

Most animals reproduce sexually

• Dominant diploid stage

• Cleavage = 1st major phase of embryonic development

• rapid cell division after fertilization

• Cleavage leads to formation of a blastula

• The blastula undergoes gastrulation (2nd major phase)

• Formation of layers of embryonic tissues

Describe the basic animal body plan

• symmetry

• presence of true tissues (organized groups of cells that work together to perform specific functions)

• number of embryonic layers

• other details of embryonic development

• presence of a body cavity

Define “body plan”

the sum of the general features of an animal’s form.

Describe the animal phyla poriphera

Sponges

• are simple animals with porous body, usually lack body symmetry, are usually marine, do not have true tissues

• Two cell types

• Flagellated choanocytes filter food from water, Amoebocytes digest & carry food

• Sponges represent the earliest branch of the animal kingdom

Describe the animal phyla cnidaria

• Cnidarians have

• diploblastic (two true tissue layers), radial symmetry, feeding through gastrovascular (single) opening, tentacles with stinging cells

• Two body forms:

1. polyp (such as hydras) adheres to a substrate, extends tentacles

2. medusa (such as jellies) swim freely with tentacles dangling downward

Describe the animal phyla platyhelminthes

• All three phyla of worms are triploblastic protostomes

with bilateral symmetry, but

• flatworms (Platyhelminthes) are acoelomates

• roundworms (Nematoda) are pseudocoelomates

• annelids (Annelida) are coelomates

• Flatworms have a gastrovascular opening & a simple nervous system and are species that live in marine, freshwater, damp land habitats. Some are animal parasites (i.e., tapeworms).

• Roundworms (= nematodes) have a periodically-shed, protective cuticle, a complete digestive tract with a mouth & anus, Some are free-living decomposers, while others are

plant or animal parasites.

Describe the animal phyla nematoda

• characterized by their elongated, cylindrical bodies, that are tapered at both ends

• possess a complete digestive system (Mouth and Anus)

• covered by a tough, flexible cuticle that is periodically molted

describe the animal phyla mollusca

Mollusks are triploblastic protostomes, coelomates, bilaterally symmetrical

• A mollusk body divided into

three main parts:

• a muscular foot, which functions in locomotion, a visceral mass containing most of the internal organs, a mantle, which may secrete a shell, most mollusks have open circulatory system (i.e., no blood vessels)

describe the animal phyla annelida

• species that include land & marine worms as well as some animal parasites

• a nervous system & a complete digestive tract

• a closed circulatory system in which blood remains enclosed in vessels.

describe the animal phyla arthropoda

Arthropods are bilaterally symmetrical, triploblastic protostomes & coelomates

• This phylum has over a million species including myriapods (subphylum), crustaceans (subphylum), arachnids (class), & insects (class).

• Their diversity & success are due to their segmentation, hard exoskeleton, & jointed appendages.

• As an arthropod grows, it must periodically molt.

• Molting is shedding of an old exoskeleton & secretion of a larger one.

describe the animal phyla echinodermata

• triploblastic deuterostomes & coelomates (along with phylum Chordata)

• all marine including sea stars & sea urchins

• slow-moving or sessile

• radially symmetrical as adults

• Echinoderms have

• a water vascular system (canals & tube feet), a unique hydraulic system for movement

• an endoskeleton of hard calcium-containing plates

• the ability to regenerate lost arms

Define segmentation, explain its functions, and note the

animal phyla where it occurs.

• the subdivision of the body along its length into a series of repeated parts

• used for movement and flexibility, specialization, regeneration, growth

• occurs in arthropoda, and annelida

Describe the common characteristics of insects

Insects are the most successful group of animals

• a life cycle with short generations & large numbers of offspring

• Insect life cycles often include metamorphosis (body form changes from larva to adult).

• The body of many insects includes

• a head, thorax (middle section), abdomen, three sets of legs, and wings (in most)

List several representative species within the eight

invertebrate animal phyla

Sponges (Porifera), Jellyfish (Cnidaria), Earthworm (Annelids), tapeworms (platyhelminthes), roundworms (nematoda) Land Snail (Mollusca), millipede (arthropoda)

List four features of chordates

dorsal hollow nerve cord, notochord, pharyngeal slits, and a post anal tail

Describe the key derived traits of the chordates

• Vertebral column (Spine/Backbone)

• Hinged Jaws

• Lungs or Lung derivatives

• lobed fins

• legs

Describe the key derived traits of the chordate subgroups

a notochord, dorsal hollow nerve cord, pharyngeal slits, endostyle/thyroid gland, and a post-anal tail

Hagfishes

deep-sea scavengers that produce slime as an antipredator defense

• have a rudimentary vertebrae

• lack hinged jaws

Lampreys

parasites that penetrate the sides of fishes with their rasping tongues

• have rudimentary vertebrae

• have a notochord for the body’s main

support

• lack hinged jaws & paired fins

Sharks/Rays

• have a flexible skeleton made primarily of cartilage

• have gill slits and skeletal rods, paired fins

Ray-Finned Fishes

• have a skeleton made of bone & fins supported by thin, flexible bony rays

• gill slits, paired fins, skeletal rods

Lobe-finned fishes

have a skeleton made of bone & a series of rod-shaped bones in their muscular pectoral & pelvic fins.

• coelacanths, lungfishes, tiktaalik

Define tetrapods

jawed vertebrates with limbs & feet that can support weight on land.

Amphibians

tetrapods, vertebrates with 2 pairs of limbs

include salamanders, frogs, &

caecilians

• use their moist skins to supplement their lungs for gas exchange

• usually lay their eggs in water

• were the first tetrapods to colonize land

Reptiles

• amniotes (tetrapods with terrestrially-adapted egg).

include lizards, snakes, turtles, crocodilians, & dinosaurs

• have a skin covered with scales & waterproofed with keratin

• obtain most of their oxygen using lungs

• are ectothermic, absorbing external heat rather than

generating much of their own.

Birds

feathered reptiles

• Most can fly & their bodies reflects adaptations for flight.

• Birds are endothermic, using heat generated by metabolism

to maintain a warm, steady body temperature.

• also dinosaurs

Mammals

• endothermic amniotes with

  • hair, which insulates their bodies

  • mammary glands, which produce milk

• have efficient respiratory and circulatory

  systems that support their high rate of metabolism.

• teeth are

  differentiated for many

  kinds of diets.

Describe the transitional species Tiktaalik

lobe-finned fish with lungs & structures resembling both fins & limbs

Describe the transitional species Acanthostega

had fish-like features (gills & a tail fin) & tetrapod traits (limbs with digits)

describe monotremes

egg laying mammals- platypus

describe marsupials

gestate briefly & give birth to tiny, embryonic offspring that develop while attached to the mother’s nipples.- Kangaroo

Describe Eutharians

have fully developed placenta & give birth to fully developed young (e.g., humans).

What are the 3 main groups of living primates?

1. Lemurs, lorises, and bush babies

2. tarsiers

3. monkeys and apes

what are the defining characteristics of monkeys

• walk on all 4s

• found in both old world and new world (Central and south America

• smaller than apes

• have tails

what are the defining characteristics of apes

• Only found in old world (Africa and Asia)

• can be bipedal (two rear legs)

• larger than monkeys

• larger brains than monkeys

• more flexible behavior

• no tail

Describe the evidence that suggests when upright posture and large brains first evolved in hominins.

Bipedalism arose millions of years before larger brain size.

• A clue to bipedalism is the location of the opening in the base of the skull through which the spinal cord exits.

Describe the relationships between Neanderthals and modern humans.

• Neanderthals & humans overlapped in Europe & western Asia for thousands of years.

• most non-Africans today have around 1–2% Neanderthal DNA