evolution of animals Flashcards
what are animals
- eukaryotes
- multicellular
- heterotroph
- aerobic
what are the characteristics of animals
- able to move
- sexual/asexual reproduction
- cells organized into tissues
- development goes through blastula stage
- no cell wall
what does multicellularity require
evolution of cell adherence (attachment) and cell signaling (communication)
what are cadherins
proteins involved in cell-to-cell attachment
what do sponges have
choanocytes: resemble choanoflagellates (feeding by filtration)
amoebocytes: transport nutrients to other cells, can differentiate into any other cell
what life cycle do animals go through
diplontic
examples of asexual reproduction in animals
- budding in jellyfish
- fragmentation in sponges/flatworms
- parthenogenesis: females produce offspring from unfertilized eggs
what are the types of symmetry in animals
- radial symm
- bilateral symm
what are hox genes (homeotic genes)
regulatory genes that control placement of body part
–> control developmental fate of groups of cells
what are larva
sexually immature phase that is morphologically distinct from adult
what is metamorphosis
developmental transformation that turns animal into juvenile that resembles adult
–> not sexually mature yet
what is a blastula
when diploid zygote ungerdoes mitosis
what is gastrulation
formation of gastrula through infolding
–> forms embryonic tissues that will develop into adult body parts
what are the types of cell division
- spiral cleavage : oblique to body axis
- radial cleavage: parallel to body axis
- determinate cleavage: each cell defines specific part of embryo
- indeterminate cleavage: each cell has potential to produce complete embryo
what does the blastula develop into
- protosomes: the mouth
- deuterostomes: anus
what are the characteristics of protosome development
- spiral cleavage
- determinate
- mouth develops first
what are the characteristics of deuterosome development
- radial cleavage
- indeterminate
- anus forms first
what embryonic tissues do animals with radial symmetry have
- ectoderm (outer layer)
- endoderm (inner layer)
dipoblastic
what embryonic tissues do animals with bilateral symmetry have
- ectoderm
- mesoderm
- endoderm
tripoblastic
what is the coelom
cavity lines by tissues derives from mesoderm between digestive track and outer body layer
what are the functions of body cavities
- structural support
- transport and diffusion
- allows for growth of organs
what are triploblastic animals with no coelom called
acoelomates
–> more efficient digestion
what is embryogensis
infolding of neural plate forms neural tube and structures of nervous system
what is the notochord
dorsal, longitudinal, flexible rod along anterior-posterior axis of chordates
how does surface/volume ratio of animals affect them
surface area smaller for larger organisms, heat loss is decreased
what is homeostasis
steady-state physiological condition of body
what is thermoregulation
mechanism for regulating body temp
endotherm vs. ectotherm
endotherm: source of heat is internal (metabolism)
ectotherm: source of heat is external (sunlight)
homeotherm vs. poikilotherm
homeotherm (regulator): attenuates variations of internal environ. when external environ. changes
poikilotherm (conformed): variations of internal environment can be tolerated when external environ, fluctuates
what is osmoregulation
regulation of animal’s water loss
what are invertebrates
animals with no backbone (spine)
->95% of species
what are ecdysozoa
protostome animal that creates exoskeleton periodically molted
what can protostome animals possess either of
lophophore: crown of ciliated tentacles around mouth
trochophore: larval stage
what do chordates possess
- a notochord
- dorsal nerve chord
- pharyngeal slits behind mouth (filtration)
- post-anal tail
what is paedomorphosis
retention in adult of juvenile features of its ancestors
what are vertebrates
animals with a spinal cord
–> muscle attachment
what are cyclostomes
vertebrates with NO jaws
–> circular mouth
- cartilage skeleton, no collagen
what are gnathostomes
vertebrates WITH jaws
- modification of 2 skeletal rods
–> jaws
–> support structures
- anterior gill slits (suspension feeding, gas exchange)
what are chondrichthyes
cartilaginous fish
–> have placoid scales
what are the 3 modes of reproduction for chondrichthyes
- oviparous: egg laying, external hatching
- ovoviviparous: embryo feeds from egg yolk, hatches into uterus
- viviparous: embryo feeds from mother through placenta until birth
what are osteichthyes
bony fish
–> made of calcium phosphate
–> have swim bladder
–> mostly oviparous
what are tetrapods
four limbs with digits
–> new land niches
what are the adaptations that lead to the colonization of animals to land
- support of body against gravity
- breathing air
- hearing in air
- resistance against dry environments
- vascular system with lungs/organs
what are the stages for amphibians
1) aquatic larval stage
2) metamorphosis (loss of tail, formation of legs)
3) terrestrial predator adult
what are amniotes
clade of tetrapod vertebrates comprising the reptiles, birds, and mammals
what are the 4 embryonic membranes for amniotes
- chorion: outer membrane (gas-exchange)
- amnion: surrounds cavity
- allantois: surrounds disposal sac (metabolic waste)
- yolk sac
what do reptiles have
- dry skin with scales
- ectothermic (except birds)
- improved locomotion
what are the characteristics of birds
- feathers became an exaptation
no bladder
light skull for flying
what are characteristics of mammals
- produce milk
- endothermy
- large forebrain
- hair/fat layer under skin (insulation)
- kidneys
what are characteristics of primates
- thumbs
- large brain, short jaw
- parental care and social behaviours
- hand-eye coordination
- overlapping visual fields
what are characteristics of humans
- bipedal
- language
- homo neanderthalensis closest relative species
