1: Problems of Life, Animal Classifications & Relationships Flashcards
What defines an animal?
multicellular motile (at least in one life stage) heterotrophic arise from embryos produce gametes
All animals must do this to survive
get food get oxygen keep water balance (to control internal solutes) removes metabolic wastes reproduce
How do they solve the problems to survive
Solutions arise from environment, lifestyle, and size via the process of evolution
Humidity (life challenges)
1: Aquatic
2: Terrestrial
1: High = gills, dissolving excreta
2: Low = internal breathing organs, solid or liquid excreta
Density (life challenges)
1: Aquatic
2: Terrestrial
1: High = less physical support needed
2: Low = stronger physical support needed
Temperature Fluctuations (life challenges)
1: Aquatic
2: Terrestrial
Low = water buffers extremes of temperature High = spp need ability to manage body temperature
Oxygen Solubility (life challenges)
1: Aquatic
2: Terrestrial
Low = 6-8 ml/L at best High = 210 ml/L of air
Viscosity (life challenges)
1: Aquatic
2: Terrestrial
!: High high friction against movement but, lower fall risk
2: Low = less friction against movement, but higher fall risk
Light (life challenges)
1: Aquatic
2: Terrestrial
1: Low at depth - animals may be far from primary producers
2: High unless underground - animals close to plants
Nutrients (life challenges)
1: Aquatic
2: Terrestrial
1: Easily absorbed form dissolved sources in water
2: Not available from air. Need to find other ways to obtain (especially in water)
Define sessile
fixed in one place; immobile.
Locomotion
1: Bilateral symmetry animals
2: Radial symmetry animals
free-moving
sessile
Radial Symmetry
a type of structure of an organism or part of an organism in which a vertical cut through the axis in any of two or more planes produces two halves that are mirror images of each other
Bilateral Symmetry
symmetry in which similar anatomical parts are arranged on opposite sides of a median axis so that one and only one plane can divide the individual into essentially identical halves
SA:V ratio falls as length increases
1: Aquatic environments
2: Terrestrial environments
1: where diffusion is occurring, so SA maximized
2: where animals are trying to prevent water loss they try to minimize SA to volume ratio
Small animals (shape)
Use diffusion for gas exchange, excretion and transportation
Large animals (Shape)
Have coeloms and blood vascular systems and fold and coil their viscera to fit compactly into the body
zygote define
a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum
Blastula define
an animal embryo at the early stage of development when it is a hollow ball of cells
Grastrula
an embryo at the stage following the blastula, when it is a hollow cup-shaped structure having three layers of cells.
Radial symmetry animals.
Complete gut forms
Pseudocoelomate
Acoelomate
Coelomate
Pseudocoelomate define
an organism with body cavity that is not derived from the mesoderm, as in a true coelom, or body cavity.
eg. invertebrates (nematodes and rotifers)
Acoelomate
an animal that has no internal, fluid-filled body cavity separating its body wall from its digestive tract.
- packed solid with cells
eg. group comprising the flatworms and nemerteans characterized by bilateral symmetry and a digestive cavity that is the only internal cavity
Coelomate
have a body cavity called a coelom with a complete lining called peritoneum derived from mesoderm (one of the three primary tissue layers).
eg. metazoans
metazoans
animals that develop from an embryo with three tissue layers
three tissue layers
ectoderm, mesoderm, and endoderm
Diploblastic define
animals that have two layers of cells (ectoderm and endoderm) in the embryo which give rise to all organs
acoelomate eg. cnidarian
Triploblastic
animals that have a third cell layer in the embryo mesoderm
acoelomate
eg platyhelminthes
coelomate
eg. echinoderm, mollusc, chordate (larger animals)
Species generally defined as
having the capacity to reproduce successfully to produce fertile offspring
Taxonomy hierarchy classification system
Domain Did Kingdom King Phylum Phillip Class Come Order Over Family For Genus Good Species Soup
Evolution
Processes by which new types of life occur on earth
works via inheritance and death
if they die then genes do not pass on.
only events before or during reproduction that are important
Systematic define
Study of biological diversity and its classification,
produces classifications that best express the relatedness of organisms
what studies are combined into systematics
morphology, embryology and genetics
Cladistics
a method of classification of animals that aims to identify and take account of only those shared characteristics which can be deduced to have originated in the common ancestor of a group of species during evolution, not those arising by convergence
Convergence
the tendency of unrelated animals to evolve superficially similar characteristics under similar environmental conditions
phylogeny
history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms.
Homologous define
similar in position, structure, and evolutionary origin but not necessarily in function
characters indicating common ancestry must be homologous
Analogous
Analogous
performing a similar function but having a different evolutionary origin, such as the wings of insects and birds
What does molecular genetics use
What can it tell us
Hox genes, rRNA, mtDNA and other sequences.
how many steps separate species
What cant molecular data do
resolve the precise sequence of steps
tell us the selection pressures
predict what unfossilised ancestors looked like
resolve the order of divergence in rapidly diversifying species
Hox (or homeotic) genes
what do they do
control the embryonic body along the anterior-posterior axis
activate or repress genes
rRNA
18s rRNA is structural for eukaryotic ribosomes, the sequences have slow evolutionary rates suitable for phylogenetic analysis
mtDNA
Originates from mitochondrion, in most species inherited solely from the mother (only in egg). Hasnt changed much through history so useful in phylogenetics and population differentiation.
