vertebrate diversity (PP21) Flashcards
explain and show chordate characteristics in humans
Notochord eventually forms spinal disks between vertebrae in our spine
Hollow dorsal nerve cord remains as our spinal nerve cord
Pharyngeal slits disappear during embryonic development
Post-anal tail eventually reduces during embryogenesis & no longer exists in adult
Coccyx (tail bone) = remains of a structure that is longer in many other chordates
what are the invertebrate chordates
Cephalochordates (
Urochordates
explainn cephalochordates and give an example
(e. g. Lancelets)
- Named for their blade-like (lance-like) shape
- Sessile as adults
- Marine suspension feeders that retain the characteristics of the chordate body plan as adults
explain urochordates and give an example
(e. g. Tunicates)
- Belong to the deepest-branching lineage of chordates
- Marine suspension feeders (commonly called sea squirts)
- Most resemble chordates during their larval stage (may be as brief as a few minutes) –only retain pharyngeal slits
explain class myxini and give examples
“Jawless fish” (Agnathostomes)
- Display all the features of craniates, but least derived
- Have a cartilaginous skeleton derived from notochord, but no vertebrae
- Not actually “vertebrates”
- Have teeth, but no jaw, and so generally dwell near the bottom of the ocean, or attach and feed parasitically off of other animals
ex: hagfish and lampreys
explain gnathosomes
Vertebrates with jaws
Jaws evolved from skeletal rods of pharyngeal slits
Enhanced sensory systems (including the lateral line system) Extensively mineralized endoskeleton Paired appendages (“limbs”)
What are the The earliest gnathostomes in the fossil record
extinct lineage of armored vertebrates called placoderms
explain class Chondricthyes and give example
“Cartilaginous fish”: internal skeletons of cartilage
Modified from mineralised skeleton
Posses a (toothy) jaw Allows consumption of tougher foods
Paired fins
Formation of vertebrae
Cartilage skeleton that forms around the dorsal hollow nerve cord
Internal fertilisation (involves physical copulation between male & female) The embryonic shark often develops inside the mother (live birth)
ex: sharks and rays
explain Class Actinopterygii and give example
“Bony fish”: mineralized (ossified) calcium-based skeletons
Similar composition to mammalian skeleton
Most use external fertilisation (oviparous)
Some fish fertilize internally like chondrichthyes
Scales & mucus secretion to reduce drag
Use gills to extract oxygen from the water
Air can be stored in a swim bladder
Gas stored or released to maintain buoyancy
ex:rayfish
explain Sarcopterygii
Also “bony fish”: mineralized calcium-based skeletons
Developed sturdy, skeletally supported, lobe-like fins
Groundwork for terrestrial limb
Divided into 2 classes:
Actinista (Coelocanths)
Deep-sea species thought extinct until capture in 1938
Dipnoi (Lungfish)
Have primitive lungs (possible that ancestors capable of breathing air directly)
explain tetrapods
-Gnathostomes with 4 locomotory limbs (able to walk)
(Evolutionary advantage to living on land, even if partially because they can avoid marine predators)
Terrestrial environment would provide a large variety of food & resources without many initial competitors
Prior to tetrapods, very few animals had transitioned to become terrestrial: great potential for the first tetrapods
explain class amphibia
Amphibians: ~5500 species
-First terrestrial tetrapods
For earlier organisms that originate from the water, there -must be a good way of keeping wet
-Most amphibians have moist skin that complements the lungs in gas exchange
-Bones & structures require additional strength to counter gravity
-Reproduction requires assistance (ancestor relied on external fertilisation)
what was the solution to ambient who needed assistance for reproduction
Solution: lead “double” lives - spend portions of their lives in both land & water
To successfully mate, intercourse must take place in the water
Zygote develops in water (tadpole)
Tadpoles resemble simple chordates (gills, no limbs)
As the amphibian matures, it will grow limbs & eventually become terrestrial, relying on its lungs to breath
what are amniotes and explain
Group of tetrapods including reptiles, birds, mammals
Named for the amniotic egg (major derived character of the clade)
Contains specialized membranes that protect the embryo
Other terrestrial adaptations:
Relatively impermeable skin
Ability to use rib cage to ventilate the lungs
what are the parts of the amniotic egg
Amnion
Yolk sac
Allantois:
Chorion
explain amnion
Amnion: membrane surrounding fluid-filled compartment that contains the embryo – provides protection & padding
explain yolk sac
stores nutrients, & blood vessels grow into it to help extract nutrients
explain allantois
used to export the waste
explain chorion
: membrane that allows selective movement of gases so embryo can breathe
explain class reptilia
Includes lizards, snakes, turtles, tuatara, crocodilians, birds, & the extinct dinosaurs
Well-adapted to terrestrial life
Reproduce sexually without the need to return to water
Internal fertilization but not live birth - lay eggs
Keratin scale provide waterproof barrier
Temperature regulation:
Most reptiles are ectothermic
Absorb external heat as the main source of body heat
Birds are endothermic
Capable of keeping the body warm through metabolism
explain class aves
Grouped as descendants of dinosaurs
Lay eggs like reptiles
Tend to care for them (except cuckoos – brood parasites)
Capable of flight!
Specific adaptations enable flight.
Birds, like their therapod dinosaur ancestors are bipedal, freeing their forelimbs for other functions (like flapping)
Lighter bones – MYTH! (bones have hollow areas to serve as air pockets for respiration, but bones are denser to give better support – end up weighing the same!)
Lungs connected to air sacs to facilitate gas exchange & store air (use huge amounts of energy for flight)
Specialised feathers are derived from scales
Lack teeth: ingest pebbles to help break down food in their gizzard
do birds have lighter bones?
nO
bones have hollow areas to serve as air pockets for respiration, but bones are denser to give better support – end up weighing the same!)
explain feathers
Feathers are modified scales (first adapted for insulation?)
Down feathers for conserving body heat
Hydrophobic properties to repel water during flight
Aerodynamic feathers for lift
EXPLAIN class mamalia
More than ~5000 species
Distinguishing characteristics:
-Mammary glands (produce milk for suckling young)
-Keratin-based hair or fur (insulation)
-Larger brains than other vertebrates of equal size
-Heterodonts (different specialized teeth)
-4-chambered heart
-Endothermic (warm-blooded)
-Can be nocturnal (generate own body heat)
(Energetically costly (faster metabolism))
ex: dogs
explain heterodonts
Different types of teeth for different functions:
Cutting / tearing (incisors)
Holding food / weapons (canines/fangs)
Chewing / grinding (premolars &molars)
explain order monotremata
Traits reveal the transition from more reptile-like ancestor to mammals:
- Do not give live birth: lay eggs
- Platypuses, for example, have bills & males have poisonous claws
- Have mammary glands but no nipples
- Milk is secreted onto hairs
platypus
what subclass is monotremata part of ?
Subclass Protheria (but everyone else there is dead)
explain order metatheria
Also called marsupials
Give live birth but offspring are underdeveloped
Advantages of live birth:
Mother remains mobile & capable of seeking food or shelter
Mother can provide constant protection to embryo
Disadvantages of live birth:
Limit to how developed the offspring can be at birth
In marsupials, infants are very small & must be transported by the mother in a specialized pouch during further development
Mammary glands connected to nipples (located inside pouch)
kangaroos and opossums
what are eutharians
Have placenta
Serves as a filter between mother & developing young for removal of waste products
Allows gas exchange
Offers immunological protection
Placenta allows infants to develop further than marsupials inside womb (also means longer gestation period)
what is the placenta
specialized nutrient-containing organ present in the mother during the development
explain order primates
Derived (novel) characters of primates:
Hands and feet adapted for grasping with fully opposable thumbs
Large brain & short jaws
Forward-looking eyes close together on the face (providing stereoscopic vision)
Well-developed parental care and complex social behaviour
simians and monkeys
DIAGRAM ON NOTES
explain hominids
All hominoids have relatively long arms, short legs, & no tail
apes
explain family hominidae
Includes humans, chimpanzees, gorillas, & orangutans
Humans are most closely related to chimpanzees
Diverged from our common ancestor ~5 to 7 million years ago
GREAT APES
explain species homosapiens
Homo sapiens are ~160,000-200,000 years old
Distinguishing characteristics:
- Upright posture & bipedal locomotion
- Larger brains
- Language capabilities
- Symbolic, abstract thought
- Manufacture and use of complex tools
- Shortened jaw & possess chins
- Swiveling neck
