lecture 15 Flashcards
1
Q
chordates
A
- chordates clades were constructed by analysis of:
- molecular evidence
- anatomical evidence
- fossil evidence
- tunicates were thought to be the first group of chordates
- only chordates clade that does not have brain
- all other clades have a brain
- wide variation in brain sizes
- chordates that contains a head are referred to as craniates
- head consists of brain
- located at anterior end of the dorsal nerve cord
- contains a skull and all sensory organs
- eyes, ears, nose
- innovations allowed for active predation
- defined by the presence of an extensive, well defined backbone
- vertebral column
- composed of vertebrae
- functions to protect the contents of the nervous system
2
Q
evolutionary tree chordates
A
- the next major evolutionary development was that of jaws
- followed by lungs and then muscular lobed fins with skeletal support
- tetrapods: jawed vertebrates with two pairs of limbs
- the first vertebrates on land
- amniotes: tetrapods with a terrestrially adapted egg
- this was the last major adaptation to life on land
3
Q
hagfishes and lampreys
A
- most primitive chordates
- both are craniates
- both are jawless
- hagfish have a notochord
- strong flexible rod running the length of the fish body
- lamprey have a rudimentary vertebral column
- notochord also present
- classified as vertebrates because of VC
4
Q
hagfish
A
- approximately 40 species
- scavenge dead or nearly dead vertebrates
- along the bottom of the ocean
- almost blind
- excellent sense of smell and touch
- enter prey through existing holes
- or create holes using sharp structures on the tongue that resemble teeth
- they grasp and tear flesh
- excludes slime from glands on the sides of its body
- occurs when threatened
- after threat is removed the hagfish ties its tail in a knot and slides the knot forward to remove the layer of slime
5
Q
lampreys
A
- oldest living vertebrates
- suspension feeders
- live in freshwater streams
- most of the time in spent bried in sediment
- migration to the ocean or the sea
- occurs when they mature into adults
- most are parasitic
- attaches to the skin of prey using rasping tongue to penetrate
- fees on blood and tissues
6
Q
jawed vertebrates
A
- appeared on fossil record 470 million years ago
- have paired fins and a tail
- allows them to swim to their prey
- jaws enable them to catch and eat a diverse group of prey
- contrast with suspension feeders
- jawed vertebrates with paired fins and gill are commonly referred to as fish
- initially skeletal rods supported the gill slits functioned to trap food particles
- two pairs of skeletal rods near the mouth have become the jaws and their supports
- three lineages:
- chondrichthyans
- ray-finned fish
- lobe-finned fish
7
Q
chondrichthyans
A
- sharks and rays
- flexible skeleton made of cartilage
- some sharks are suspension feeders
- eat small floating plankton
- most are predators
- quick swimmers with strong jaws
- sharp vision
- great sense of smell
- electrosensors on the head
- detect electromagnetic fields produced by muscles contractions of near by animals
8
Q
sharks have lateral line systems
A
- a row of sensory organs that run along each side of the animal
- sensitive to changes in water pressure
- can detect very small vibrations caused by animals moving nearby
9
Q
rays are adapted for life at the bottom of the ocean
A
- bodies are dorsoventrally flattened
- eyes on top of the head
- tail has sharp spines with venom glands at the base
- suspension feeders, swim through the ocean filtering plankton
10
Q
ray-finned fish
A
- tuna. trout, and goldfish
- skeleton made of bone
- reinforced with cartilage
- hard matrix of calcium carbonate
- usually flattened scales over the skin
- secrete a mucus to reduce drag while swimming
- operculum: protective flap on each side of the head
- covers the chamber housing the gills
- movement of the operculum allows the fish to breathe without swimming
- contrast: sharks need to swim to pass water over their gills
- swim bladder: gas filled sac
- a lung derivative
- helps keep the fish buoyant
- evolved from balloon like lungs
- the largest group of vertebrates
- over 27,000 species
11
Q
lobe-finned fish
A
- rod-shaped bones
- found in muscular, pectoral, and pelvic fins
- three lineages:
1. coelacanth: deep-sea dweller
2. lungfish: inhabit stagnant waters (water that doesnt flow) - gulp air into lungs connected to the pharynx
3. tetrapods: adapted to life on land - gave rise to terrestrial vertebrates
12
Q
amphibians
A
- salamanders and frogs
- tetrapods
- verebrates with two pairs of limbs
- most are found in damp habitats
- moist skin supplements lungs for gas exchange
- skin usually has posion glands used in defense
- first vertebrae to colonize land
- distribution of most amphibians is limited because they require moisture because they are susceptible to dehydration
- some amphibians live only on land
- toads
13
Q
reptiles
A
- lizards, snakes, turtles and birds
- dinosaurs were reptiles
- amniotes
- major character that was derived here is the amniotic egg
- embryo develops inside enclosed by a protective fluid-filled sac called amnion
- allows reptiles to complete their life on land
- similar to the role of the seed in plant evolution
- snakes likely became limbless because their ancestors developed a burrowing lifestyle
14
Q
other reptile adaptions
A
- reptilian skin: covered with scales, heavily keratinized to prevent drying out
- as a result reptiles may not breath through skin
- breath using a lung, assisted with a rib cage
- non-bird reptiles are referred to as cold-cold blooded
- do not use metabolism to generate body heat
- to stay warm they stay in the sun or maintain contact with warm surfaces
- absorbing heat rather than generating heat is referred to as actothermic
- previous reptiles such as dinosaurs are thought to have been endotherms
- dinosaurs are extinct today
- the reptilian group birds are descendante of one dinosaurs lineage
15
Q
birds
A
- evolved from theropods
- a small two legend group of dinosaurs
- suggested by fossil evidence
- feathers present on these dinosaurs
- not used for flight
- likely used for insulation and courtship displays
- archeaopteryx, the most primitive bird
- feathered wings
- otherwise more dinosaur like
- winged claws
- teeth
- tail with lots of vertebrae
