Topic 2: Animal diversity pt 2 Flashcards
did vertebrates start on land or water
water, Vertebrates inhabited the oceans for more than 150 million years before emerging on land
what are the 3 major groups of vertebrates that have since transitioned back to living in the ocean?
Cetaceans (whales and dolphins)
Sirenians (manatees)
Pinnipeds (seals and walruses)
all vertebrates are in chordata, so what 3 features do all vertebrates have?
bilateral symmetry, triploblastic, deuterostome development
what 4 derived characteristics do all chordates have
notochord, dorsal hollow nerve cord, pharyngeal gill slits/clefts, muscular post-anal tail
what are the groups of invertebrates within chordata
cephalochordata (lancelets), and urochordata (tunicates)
what clade is the basal taxon of the chordates
cephalochordata
because moleculary they’re least like the rest of the chordates
how do cephalochordata larvae feed vs adults
larvae feed on plankton by swimming upwards and passively sinking, adults bury themselves in the sand of the seafloor and become like suspension feeders.
how do adult cephalochordata (lancelets) swim
by undulating side to side
are urochordata molecularly more related to other chordates or lancelets
other chordates
what do tunicates and all other vertebrate embryos have that lancelets don’t have. Also a diagnostic characteristic for vertebrates, describe it
a neural crest, which is a collection of cells along the edges of the closing neural tube in embryos. It gives rise to teeth, bones, cartilage in the skull, neurons, sensory capsules (for eyes etc)
what are the sister taxa and living jawless vertebrates in the clade cyclostomes
Myxini (hagfishes) and Petromyzontida (lampreys)
what taxa loses their chordate features after metamorphosis
Urochordata (tunicates), the chordate characteristics are more apparent in the larval stages than adult stages.
describe hagfishes looks, how they swim
Highly reduced vertebrae and skull made of cartilage, notochord, small brain eyes ears and nasal opening, teeth made of keratin. swim in a snake-like fashion using muscle segments.
describe lampreys looks, how they feed
parasites, larvae resemble lancelets, and are suspension feeders like lancelets.
what’s are the 4 derived characters of gnathostomes (derived = developed after common ancestor, so hagfishes and lampreys don’t have)
jaws, duplication of hox gene sets, forebrain enlarged, and lateral line system (rows of sensory organs along the body)
hagfish and lampreys lack…
jaws and backbones
what 6 animal groups are included in the gnathostomes group
chondrichthyans (sharks, rays), ray-finned fishes, amphibians, reptiles, birds and mammals
describe the body of a chondrichthyans (skeleton and shape)
their skeleton is cartilaginous, made from cells called chondrocytes. They have streamlined bodies and powerful muscles but can be clumsy.
how do chondrichthyans (sharks, rays etc, within vertebrates) float?
they store oils in their liver to help them float, and continuous swimming, if they stop swimming they will sink.
to allow gas exchange in chonrichthyans (sharks, rays) what must they do
swim continuously to allow gas exchange over their gills
how do large vs small chondrichthyans feed (sharks, rays)
large sharks (whale shark think big guy from finding nemo with straw teeth) and rays are suspension feeders, and smaller sharks are carnivores (like small viscous dog)
chondrichthyans reproduction (internal or external fertilization)
reproduction is variable, though fertilization is always internal
whats the cloaca in the shark
a common chamber used by the digestive tract and excretory system. reproductive tracts also empty into here.
describe the 3 types of reproduction (after fertilization): oviparous, oviviparous, and viviparous
oviparous: lay eggs outside the body (just egg), oviviparous retain fertilized eggs in the oviducts, offspring are birthed after they hatch (so egg + live birth), viviparous: young develop in uterus and obtain nutrients through a yolk sac placenta
how do rays feed
they are bottom dwellers they eat molluscs and crustacean, their tails can contain venomous barbs
what are the types of fish included in the osteichthyans clade, common and latin names)
ray finned fish (actinopterygii), and lobe finned fish (sarcopterygii)
what are the derived characteristics of osteichthyans
ossified (bony) endoskeletons, swim bladders (to control buoyancy) derived from lungs,
how do osteichthyans swim efficiently?
they have scales and secrete mucus to reduce drag while swimming.
osteichthyans reproduction
reproduction is mostly oviparous with external fertilization
how are ray fish important and how have humans affected their populations
economically important to humans because they are a big source of food, industrial harvesting has reduced fish populations
3 main lineages of lobe-finned (sarcopterygii)
- Coelacanths (actinistia) 2. Lungfishes (dipnoi) 3. evolved to become tetrapods
what are derived characters of tetrapods
limbs with digits, head separated from body via neck, pelvic girdle fused to backbone (allows for independent movement of arms and legs), loss of gills, pharyngeal gill slits became ears, glands and etc.
what is the origin of tetrapods
things got stuck in shallow pods and may have used fins to try to move to new water sources.
where do amphibians live
on land and in water (toads are basically terrestrial frogs but still amphibians).
list and describe the stages of the amphibian (frog) life cycle
- The larval stage is the tadpole, aquatic, herbivorous with gills. no legs swims by undulating
- metamorphosis leads to development of legs, lungs, eardrums, and a carnivorous adapted digestive system, gills disappear and lateral line system also disappears.
- adults return to the water to mate
what habitat do amphibians require, why?
moist/wet habitats to allow for gas exchange across their skin. Their eggs also have no shell so they must lay their eggs in water.
describe amphibians reproduction
fertilization is external, male sperm fertilizes eggs the same time they are released.
how did amniotes adapt from Tetrapods
their eggs adapted to be terrestrial (unlike frog eggs designed for water), an amniotic egg with 4 membranes
what are the amniotic egg 4 membranes, list and describe
- the amnion: encloses the amniotic fluid
- the yolk sac: attached to the embryo, contain nutrients
- the allantois: disposal sac for metabolic waste of embryo (this includes CO2, so also involved in gas exchange)
- the chorion: outermost membrane for gas exchange.
what animals are included in the reptiles
tuaturas, lizards, snakes, turtles, crocodilians and birds
what are the derived characteristics of reptiles that amphibians don’t have, whats the exception
scales composed of keratin, lay shelled eggs on land (not water), ectothermic: absorb external heat as main body heat source. exception: birds are endothermic (maintain body temp via internal metabolism)
what characteristic do diapsids have (within amniotes)
pair of holes on each side of skull to help control jaw movement
what animals are within archosaurs (amniotes)
crocodilians, pterosaurs, dinosaurs, birds. (birds are last known living dinos)
what animals are in lepidosaurs (amniotes), what do they eat
tuataras, and squamates (snakes, lizards). they eat eggs, insects, small lizards
turtles are diapsids, but what characteristic did they lose
holes in the skull
what are the most modified animal of the archosaurs? whats different abt them
birds, lack urinary bladder, females only have 1 ovary, and gonad size reduced, hallow bones, feathers made of b-keratin, endothermic (all to be lighter for flying),
what are the derived characteristics of mammals
mammary glands: produce milk, hair and insulating fat layers, kidneys: help to conserve water when removing wastes from body, larger brain, endothermic, differentiated teeth (adapted for various food sources)
what are the 3 types of mammals
marsupials, monotremes, and eutherians
contrast marsupials monotremes and eutherians in terms of how they bear young and nurse them (nipples or no)
marsupials have placenta and give birth to live young, have nipples to make milk. monotremes lay eggs but have hair and produce milk (no nipples tho), eutherians have placenta and longer pregnancies, have nipples to make milk.
what features are unique to primates
hands and feet adapted for grasping: digits have flat nails rather than claws, ridges (fingerprints), -monkeys and apes have opposable thumbs (thumbs can move opposite to other fingers). large brain, forward facing eyes, can use tools.
what characteristics are unique to humans
bipedal (stand on 2 feet), reduced jaw bones and jaw muscles (flat faces), reduced canine teeth, shorter digestive tract
why was bipedalism adapted?
adaptation for walking in drier regions (to conserve energy and walk farther bc dry =less food (energy source) and 2 leg walking takes less energy than 4 legs so they could walk further with less food).
evolution of humans was not linear true or false
true it was not linear, there were lots of different paths and versions of humans.
