Exam 2 BIO 122 Flashcards
What are animals?
Multicellular heterotrophic organisms that ingest other organisms
Morphological diversity is used to classify/determine phylogeny of animals based on:
Symmetry
Primary tissues
Mode of development
Body cavity type
What type of symmetry do most animals have?
Bilateral symmetry.
What type of animals have radial symmetry?
Cnidaria and Echinoderms (Jellyfish and Starfish)
How many tissue layers do all animals have (except sponges) have during embryonic development?
two or three tissue layers.
Animals that have 2 tissue layers are called…
Animals that have 3 tissue layers are called…
Diploblastic
Triploblastic
What is the outer, inner, and middle layers called?
Ectoderm - outer layer
Endoderm - inner layer
Mesoderm - middle layer
These are the primary tissues present early in embryonic development, they form the animals tissues (skin, muscle, etc).
Most animals undergo development involving a ____ and a ____ stage.
blastula, gastrula
Most animal bodies are ____ and make ____ sex cells.
diploid, haploid
After an egg is fertilized…
Cells divide (cleavage) without the zygote getting larger. Then go through blastula and gastrula.
What is blastula and gastrula?
A blastula is an early embryonic stage characterized by a hollow ball of cells formed through cleavage during embryogenesis. This fluid-filled structure is crucial for the development of more complex organisms.
A gastrula is a later stage in embryonic development where the blastula undergoes a process called gastrulation, resulting in the formation of germ layers (ectoderm, mesoderm, and endoderm) and the establishment of the basic body plan of an organism.
What are the two major modes of animal body development?
Protostome - Spiral and determinate cleavage. Solid masses of mesoderm split and form coelom (formation). Mouth develops from blastopore.
Deuterostome - Radial and indeterminate cleavage. Folds of archenteron form coelom (formation). Anus develops from blastospore.
Early cell divisions can be aligned (x) or offset (y)
x = radial cleavage
y = spiral cleavage
Cells can be ____ or ____.
determinate (fated) or indeterminate (plueripotent)
Where the blastula invaginates forms either the ____ or ____ first. This begins ____.
mouth, anus, gastrulation
Animal body cavities
Acoelomates - Have no spaces between tissue layers.
Pseudocoelomates - Have a space between the endoderm and mesoderm.
Coelomates - Have a space within the mesoderm. Vertebrates are coelomates.
Which character state do you think would be the hardest to evolve repeatedly (least likely to be convergent evolution)?
a. mode of symmetry
b. body cavity/coelem type
c. radial vs spiral cleavage
d. protostome vs deuterostome gastrulation
idk yet
What are the five supergroups of animals?
Porifera, Radiata, Lophotrochozoa, Ecdysozoa, Deuterostomia.
Animals are the sister group to ____ ____.
Choanoflagellate protists - are colonial, and feed using a flagellated cell (sponges do this too).
What’s the most basal animal?
sponges
When did animals likely originate?
710-780 mya. Sponges appear in the fossil record 710 mya.
Animals underwent an explosion of diversity…
Cambrian explosion 525-535 mya. Over half of the extant animal phyla appeared within a 10 million year time span in the fossil record.
Why was there an explosion of diversity in the Cambrian?
Hypotheses:
- Preservation bias: There only appears to be a rapid diversification because earlier fossils didn’t get preserved.
- Oxygen increase lead to ecological diversity.
- Invention of predators lead to predator-prey “arms race”.
- New classes of genes allowed for rapid morphological change.
Study the pictures in discord
you fucking retard
Which hypothesis to explain the Cambrian Explosion makes the most sense to you?
- Invention of predators lead to predator-prey “arms race”.
Reasoning - Organisms developed new strategies for predation, defense, and evasion. This coevolutionary dynamic could have driven the rapid development of various body plans and adaptations during the Cambrian Explosion.
What are phylum Porifera?
Sponges - No symmetry or true tissues.
Aggregation of similar cells that perform 1 or more specific functions.
Radiata
Typified by “jellyfish”.
Have muscle and nervous tissues.
What are the specialized stinging cells in jellyfish?
Cnidocytes.
Cnidaria also have a nervous system and other specialized tissues.
What might be basal to sponges?
Ctenophores - radially symmetric, have true tissues including muscles and nervous system.
They use very different chemicals for communication and gene expression during development, is different than all other animals.
How many times did animal nervous system likely evolve?
Likely evolved twice.
How many phyla does the lophotrochozoan super group include?
18
Have a feeding structure called a lophophore.
All are triploblastic and bilaterally symmetric.
This group is defined molecularly.
All protostomes.
ex: snail
What does the ecdysozoan super group include in terms of phylum…
Arthropoda and Nemotoda.
Recognized by molecular data.
They grow by molting, they are also protostomes.
Jointed skeletons that serve as muscular support and protection.
fly, worm
What was the first animal to colonize land?
Arthropods
Deuterostomia includes phyla…
Echinodermata, hemichordata, and chordata.
Form mouth second during gastrulation.
Echinoderms are bilateral as larvae and radially/pentamerous symmetrical as adults.
Chordates have a notochord, most also have a vertebral column.
Starfish, acorn worm, (reptiles mammals amphibians etc)
Chordates are ____ animals with a ____ and a ____ ____ ____.
Segmented, notochord, dorsal nerve cord
Notochord
A flexible rod of fibrous tissue just beneath the nerve cord. Most species lose their notochord
Chordate evolution is characterized by…
Addition of characters over time.
Study pictures in discord
u fucking retard
Urochordates (tunicates)
Have larvae with chordate features, and adults that superficially resemble sponges.
Most basal chordates, more derived than cephalochordates.
What is the uniting character of the Lophotrochazoan super group?
a. A lophophore
b. Molecular characters/genetics
c. the ability to molt
d. none - they are paraphyletic
b.
Vertebrates have a well developed ____ and an endoskeleton made of ____ and/or ____.
endoskeleton, cartilage, bone
Do vertebrate chordates have a larger brain than non vertebrate chordates?
yes
What are vertebrates with jaws called?
Gnathostomes
Jaws develop from the pharyngeal slits in gnathostome embryos.
Ex: Sharks, ray finned fishes, lobe finned fishes.
Evolved paired appendages at the same time as jaws.
What are the three major living groups of gnathostomes?
Sharks, ray finned fishes, and lobe finned fishes
Chondrichthyes have ____ skeletons.
cartilaginous
Sharks, skates, and rays
What group is the most successful group of vertebrates?
“Ray finned” (actinopterygians)
Ray finned fish are very common.
“Lobe finned” fish…
(sarcopterygians)
Have muscular fin with a humerus (sometimes with a radius and ulna)
What are the two surviving groups of lobe finned fish? (not including land vertebrates)
Lung fish and Coelacanth
From what are land vertebrates derived?
Lung fish
What colonized the land and gave rise to the tetrapods?
Lobe finned fishes (365 mya)
The transition from water to land in vertebrates was ____.
gradual
The transition to land was gradual. Evolved a neck that detached their forelimbs from the head and gradually evolved the ability to support their weight with their forelimbs.
Tiktaalik - Earliest known fish with skeletal elements that are homologous to the wrist and fingers.
Tetrapods include ____ and ____.
amphibians, amniotes
reptiles (including birds) and mammals.
Amphibians are basal ____.
tetrapods
Look at chordate evolution picture in discord
you dumb stupid fluid cunt