Lecture 18: Animals Flashcards
5 key transitions for animal body plan
- symmetry
- embryonic tissue layers
- specialization of tissues and cell types
- coeloms
- segmentation
traits that unify animals
- mobility
- no cell walls
- sexual reproduction
- developed specialized tissues
- heterotrophic
- multicellular
radial symmetry
- can divide in half through multiple axes from center
- usually basal
- leads to spherical or circular organisms
bilateral symmetry
-right and left halves are mirror images
cephalization
- with half and half symmetry, different cultures can cluster in different parts of the body
- over time sensory organs are concentrated at anterior end of bilateral symmetry
- evolution of brain area
diploblastic development
-2 layers: endoderm and ectoderm
triploblastic development
- 3 layers: endoderm, mesoderm, and ectoderm
- More tissues increases complexity
endoderm
- digestive organs
- intestines
ectoderm
- outer body covering
- nervous system
mesoderm
- muscle system
- skeletal system
benefits of variable tissue
- increases complexity and specialization
- allows for differentiation of cell types which allows for more function like movement
- allowed for increased complexity of form and function of animals to become really big in size
protostome
-mouth 1st, anus 2nd “first mouth”
deuterostome
-anus 1st, mouth 2nd “second mouth”
acoelomates
- no space btwn tissue layer
- move by cilia
pseudocoelomates
- have cavity that’s fluid filled (gives them rigidness)
- fluid can also function as a hydrostatic skeleton and a circulatory system
coelomates
- have cavity inside mesoderm
- organs are lined in muscle (gives them a lot of control)
segmentation
-allow for redundancy of function and specialization
locomotion
- more efficient when segments move independently
- further protects individual organs
how has the DNA based tree changed from the old morphological tree?
- says differentiating based on coeloms isn’t correct bc both coeloms and pseudocoeloms are homoplasious
- we do still look at different types of symmetry and protostome vs. deuterostome
lophotrochozoans
-grow by adding mass to already existing bodies
edysozoans
- molt/shed hard exoskeleton in order to grow
- (NOT SNAKES)
sponges
-most basal lineage of animals
-don’t have tissues, but considered animal bc of their specialization of cells and their larvae are free moving
-can form colonies or be independent
they have a lose body structure and can vary greatly in size
ctenophores
- aka comb jellies
- homoplasious traits with more diverged animals (evolved independently)
homoplasious traits found in ctenophores
- radial symmetry
- diploblastic
- complete gut
- nerve nets
spone morphology
-contains choanocytes and water pores
choanocytes
- highly specialized cells
- long and flagellated to help sponge collect food particles as they pass
water pores
- pump water
- bring food and O2 in and waste out
cnidarians
- marine predator
- radial symmetry
- true tissues (2 layers) & nerve nets have not yet developed true organs
- incomplete gut (gastrovascular cavity)
polyps
- cnidarians
- cylindrical shaped
- usually attached to substrate like sponges
- few free swimming solitary or colonial
medusae
- cnidarians
- umbrella shaped with tentacle existing around mouth
- free swimming
cnidarian digestion
-in medusae: in gastrovascular cavity
-external digestion b/c it
takes place outside of body
the gut can then engulf those fragments
bilaterians
bilateral symmetry: protostomes and deuterostomes
-echinoderms only has radial symmetry
arrow worm placement of bilaterian tree
-deuterostome but placed with protostome
bc DNA and has a nerve cord
bryozoans and entoprocts
- colonial
- excrete protective membrane
- sexual
flatworms
- acoelomates, internal parasite, clear heads, have eyespots incomplete guts with single opening
- absorb food through body wall(diffusion)
- lack organs that transport O2 that’s why they’re flat
- have cilia, hermaphroditic, can often regenerate
tapeworm
- type of flatworm
- has no gut at all
- absorb food through body wall
rotifers
- pseudocoelomates
- complete gut
- top of lead corona
- move through cilia and depend o water to survive
rotifer corona
- circle of cilia sweep food into mouth
- cilia helps with movement and requires water to survive
ribbon worms
- similar to flatworms
- acoelomate
- complete digestive tract (both mouth and anus) have specialized feeding appendages(proboscis)
proboscis
-typically length of worm; when worm counters prey, proboscis shoots and stabs into prey so ribbon worm can eat prey
annelids
- coelomate, segmented worms (i.e. earthworms)
- segmentation allows for specialization in reproduction, digestion, excretion, feeding, respiration & locomotion
- its segments protects itself from physical damage to real brain
sea jellies and box jellies
-found in cnidarians & medusae
anemones and corals
found in cnidarians, polyp, ectoderm, and endoderm
clitellates
- aka earthworms and leeches
- annelids
- hairless
- used for wounds
polychaetes
- aka tube worms
- annelids, marines
- have a lot of hairs
- unusual forms more than 1 pair of eyes & tentacles to filter food out of water
