Chapter 34.1 Flashcards
What kind of symmetry are chordates?
Bilateral
What clades are found in phylum Chordata? (2)
Vertebrates
Deuterostomia
How do vertebrates and chordates correlate?
All vertebrates are chordates, but not all chordates are vertebrates
What is found in clade Deuterostomia?
Cephalochordates and urochordates- invertebrates more closely related to vertebrates than other invertebrates
What are 4 derived characters of chordates, and how are they maintained throughout their life?
Notochord
Dorsal, hollow nerve cord
Pharyngeal slits/ clefts
Muscular, post-anal tail
Some lost after embryonic
development
What is the notochord, where is it found, and what is it composed of?
Skeletal structure of a Longitudinal, flexible rod
Found between the digestive tube and the nerve cord
Composed of large, fluid-filled cells encased in stiff, fibrous tissue
What does the notochord provide? (2)
Provides skeletal support
Provides firm, flexible structure which muscles can work during swimming
What does the notochord develop into in most vertebrates, and in humans>
In most vertebrate, a more complex, jointed skeleton develops around the notochord
Humans notochord is reduced and forms parts of the fisks sandwiched between the vertebrae
What does the dorsal, hollow nerve cord develop from, where is it found, and what does it develop into>
Develops from a plate of ectoderm that rolls into a tube
Located dorsal to the notochord
Develops into central nervous system
What is the pharynx?
region posterior to the mouth
What is the pharyngeal cleft, and what does it develop into?
Series of arches separated by grooves from on the outer surface of the pharynx
Develops into slits that open into the pharynx
What is the function of the pharyngeal slits (2), and what does it develop into (2)?
allows water entering the mouth to exit the body without passing through the entire digestive tract
Functions as suspension-feeding devices in invertebrate chordates
Vertebrates- modified into gills
Tetrapods- do not develop into slits, but develop into ear and parts of head and neck
Where is the tail found, what does it contain, and what does it allow?
Tail extending posterior to the anus
Contains skeletal elements and muscle
Helps propel aquatic species
How do nonchordate tails differ?
digestive tract extends nearly the whole length of the body
What is the basal living chordate species?
lancelet
What shape are lancelet, and how is the derived characters maintained?
Bladelike shape
Larvae develops all four derived characteristics
Adults retain key chordate traits
What do lancelet larvae feed on?
Feeds on plankton by rising and sinking
Where are adult lancelet found, how do they feed, how do they move, and how do their muscles develop?
Found on sea floor, with only anterior exposed
Draws in water using celia, and pharyngeal slits traps food
Chevrons-rows of muscle contractions»_space;> to swim
Develops from somites- blocks of mesoderm
What are tunicates related to, and when are the derived traits found?
Closely related to chordates than lancelets
Derived traits apparent in larval stage
How do tunicates swim, and how does it develop into an adult (3)?
Tail and notochord used to swim during larval form
Looks for a substrate to settle on
Undergoes metamorphosis after settling, losing many chordate traits
Tail, notochord, and nervous system degenerates
How do adult tunicates feed (3)?
draws in water using a siphon
Water passes trough pharyngeal slit into the atrium and exits through another siphon
Food particles are trapped by cilia
What did ancestral chordates look like (2)?
Ancestral chordate may have look like lancelets
Anterior end with a mouth, a notochord, a dorsal, hollow nerve cord, pharyngeal slits, post-anal tail
What was the structure of early vertebrate brains, and how do we know>?
Vertebrate brain- elaboration of ancestral structure similar to lancelet’s brain
Same hox genes found in regions of a simple lancelet’s brain as hox genes for brain of vertebrates
How do we know genes in early vertebrate are unique to bertebrates? (2)
Tunicates possess genes associated with vertebrate organs
Absent in nonchordate invertebrates
What are characteristics of vertebrates (3), and what did they rise from?
Possess a skeletal system,
complex nervous system
efficient in capturing food and avoiding predation
chordates
How many sets of hox genes do vertebrates have, how did they arise?
Possess two or more sets of Hox genes
Through gene duplication
What genes were duplicated in vertebrates, and what did them allow>
Genes that produce transcription factors and signal molecules has been duplicated
Increasing gene complexity associated with vertebrate nervous syste and skeleton
What is the vertebrae, and how do they differ in species?
enclose the spinal cord and taken over roles of the notochord
Some species have a reduced vertebrae
What evolved in aqautic vertebrae?
Dorsal, ventral, and anal fins evolved in aquatic vertebrae
How are fins supported, stiffened, and what do they provide?
Stiffened by fin rays
Provides thrust and steering control
Supported by efficient gills
What are the only living vertebrates that lack jaws>
hagfish and lampreys
What clade do hagfish and lampreys form, and two traits they share?
Form a clade cyclostomes- living jawless vertebrates
Do not have a backbone
Notochord persists into adult hood
How does the notochord and vertebrae differ in lampreys and hagfish?
Lampreys have a sheath around the notochord
Lamprey- Possess a rudimentary vertebrae made of cartilage
Hagfish- high reduced cartilage vertebrae
Where are hagfish found, what are their bones made of, and how do they swim?
marine
Skull and vertebrae made of cartilage
Swim like a snake using muscles against their notochord
What is connected to the pharynx in hagfish, what do they feed on, and how do they defend theirself?
Small brain, eyes, ears, and nasal opening connecting with the pharynx
Bottom feeding scavengers- Feed on worms or dead fish
Slime glands used to repel other scavengers and predators
How do lampreys feed, where are they found, and what is unique about their cartilage?
Marine and freshwater
parasites that Use rasping mouth and tongue to penetrate skin of fish and ingest blood
cortilage contains no collagen
Where are lamprey larvae found, how do they feed, what do they do after maturing, and a unique characteristic of some of their larvae?
found in freshwater streams
Suspension feeders
Some species feed only as larvae
Migrate to sea after maturing
What is Haikouelia, how did they feed, and what is their body structure (2), and how did their physical characteristics emerge?
most primitive chordate fossils during the Cambrain explosion
Suspension feeder
Well-formed brain, small eyes, and muscle segment along the body- similar to vertebrate fish
No skull, ear organs- unlike vertebrates
Characters emerged as chordate nervous system complexified
What is the myllokunmingia, what is seen, body structure (2), and what did their head enable?
first chordate to have a head
Early signs of skull seen
invertebrate
Have ear capsules and eye capsules
Head enabled chordates to coordinate more complex movement and feeding behaviors
What are conodonts, when did they exist, 5 characteristics, and how long did they exist?
earliest groups of fossil vertebrate
500 million years ago
Soft-bodied, slender vertebrate
Lack jaws
Skeleton made of cartilage
Large eyes
Barbed hooks in mouth to hunt-Hardened by calcium
Abundant for 300 million years
How did bones and teeth originate, what did it evolve from, and how did the evolution begin?
Developed late in history of vertebrates
Evolved from a structure of unmineralized cartilage
Mineralization initiated as chordates egan to ingest larger food
What was duplicated in hox genes of gnathostomes, and what did it allow?
Entire genome itself has been duplicated
Enabled origin of jaws
How did vertebrates evolve until the Devonian period? (5)
Had paired fins
Inner ear with two
semicircular canals for balance
Lacked jaws
Muscular pharynx
Amored with mineralized bone
What are 4 derived characteristics of gnathostomes?
Hinged jaws used to grip and slice food
Possess additional duplication of Hox genes
Enlarged forebrain
Lateral line system
What are gnathostomes, and what do they include?
Jawed vertebrates
Includes sharks, some fishes, amphibians, reptiles, and mammals
How did hinged jaws evolve (2)?
Evolved by modification of skeletal rods previously supporting the anterior pharyngeal slits
Remaining gill slists evolved to become sites of gas exchange
What does an enlarged forebrain allow?
Enhanced smell and vision
what is the lateral line system?
organs that form a row along each side of the body sensitive to vibrations
What is the placoderms, when did they exist, and physical characteristics (3)
earleist gnathostomes
440 million
plate-skinned
paire fins and tail- easy hunting
jaws- easy grasping
What are acanthodians?
emerged at the same time as placoderms, but disappeared much later
What happened 440-420 million years ago? (2)
period of incredible evolutionary change
Diverged into chondrichthyans, ray-finned fishes, and lobe-fins
What are chondrichthyans, what do they include, and two physical characteristics?
Sharks, ratfishess, rays, and their relative
Cartilage fish
Have skeletons composed mainly of cartilage and calcium
Also have restricted distribution of bones
What does the restricted distribution of bones i chondrichthyans signify?
Signifies tha bones is a derived condition, emerging after chondrichthyans diverged from other gnathostomes
What kind of body do sharks have, how do they feed, what kind of digestive tract do they have (2)?
Possess streamlined bodies
Include suspension feeders and predators
Short digestive tract
Spiral valve- a ridge in the intestine that increases surface area and prolongs passage of food through the digestive tract
How do sharks swim (2), and what does movement provide?
Cannot maneuver well
Very dense, and sinks when swimming
Movement allows gas exchange to occur
What kind of senses do sharks have (4), and how do they detect movement?
sharp vision
cannot see color
no eardrums
nose is only used for smelling
Have regions in head to detect electric fields generated by muscle contractions
How do sharks reproduce? (4)
Egg fertilized internally
Some are oviparous- shark release fertilized eggs
Some are ovoviviparous- retains fertilized eggs, embryo hatching within the uterus
Some are viviparous- develops as an embryo and live birth
What is the cloaca?
common chamber where the execretory system empties into
How do rays feed, and where are they found?
Bottom-dwellers
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Feed using jaws to crush crustaceans
What are osteichthyans, and what do they have?
ray-finned and lobe-finned fish
Have ossified/bony endoskeleton with a hard matrix of calcium phosphate
How do fish breathe (2), how do they maintain buoyancy?
Breathe by drawing water over gills in chambers covered by the operculum- protective bony flap
Water is drawn in through mouth, pharynx, and out the gills
Maintains buoyancy by filling swim bladder with air
Evolved from lungs of tetrapods
What is found on the skin of fish, what does it secrete, what do fish also possess, and how do they reproduce?
flattened , bony scales
Secrete mucus to reduce drag
Possess lateral line system
Oviparous
What do ray-finned fish possess, what do they include, and what do they serve as?
Possess bony rays supporting fins
Common fishes we see
Serve as major sources of proteins
WHat find of fins do lobe-fins have, how common are they, and where do they live?
Lobe-fins in presence of rod-shaped bones surrounded by muscles in fins
Dwindled and only a few
remain today
Lived in brackish waters
What three lineages did lobe-fins diverge into?
Coelecanth
lungfish
tetrapods-Adapted to land and gave rise to limbs and feet
What are 5 derived characters of tetrapods?
four limbs
separate head by neck
pelvic girlde fused to backbones
most do not have gills
Ears for detecting airborne sound
What did four limbs replace, and what does it support?
Replaced pectoral and pelvic fins
Supports weight on land
What does a separate head allow?
independent movement of the head
What does a fused pelvic girdle allow?
force generated by hind legs to be absorbed better
What do tetrapods have instead of gills?
pharyngeal clefts gave rise to ears and glands
What is Tiktaalik, physical characteristic, how did they breath, what fin pattern did they possess, and what did they prove?
fossil of tetrapod ancestor
Had fins, gills, lungs, and scales, neck, and shoulder
Had full set of ribs to breath air and supprot body
Front fin had same pattern of limbed animals
Proved that wrist, ribs, and necks were ancestral to tetrapod lineage
Where were early tetrapods found?
tied to water
What does amphibian refer to, and three clades?
Refers to life stages of many frog species
Salamanders, frogs, and caecilians
How do aquatic and terrestrial salamanders differ?
Terrestrial
Side-to-side bending of the body
Aquatic
Paedomorphosis- retention of larval features even as when sexually mature
Frogs
What are frogs suited for, two things they possess, and how do they defend theirselves?
movement on land
powerful hind legs
long tongue to catch prey
secrete poison from skin glands
How do toads differ from frogs?
leathery skin and additional adaptations for life on land
What are two characteristics of Caecilians, what do they resemble, and where are they found?
Legless- secondary adaptations
Nearly blind
Resemble earthworms
Inhibit tropical area in moist soil
What do frog larval possess, and what occurs during metamorphosis (2)?
larval (tadpole) is an aquatic herbivore with gills, lateral line system, and long, finned tail
Lacks legs
Metamorphosis, develops legs, lungs, external eardrums, and digestive system for a carnivorous diet
Gills and lateral line system disappears
How do salamander and caecilian larvae differ from frogs (2)
Salamanders and caecilian larvae looks more like the adult
Carnivorous
Where are amphibians in dry found, and how do they breathe (2)?
Those in dry havitats spend time in high humidity places, like burrows and moist leaves
Rely on moist skin for gas exchange
Some lack lungs and breathe through skin
How does fertilization occur in amphibians? (3)
External
Male grasps female and spills sperm over eggs as female sheds them
Eggs are laid in water or moist environment
Characteristics of amphibian eggs (3)
Dehydrate quickly on land
Laid in large number since egg mortality is high
Some lay small numbers and is cared for
What behaviors do frogs exhibit, and examples (2)?
complex and social behaviros
Frogs are usually quiet
Some can vocalize to defend or attract females
Frog migration
Cocal communication, celestial navigation, and chemical signaling
Why are amphibians declining? 4
Chtytrid fungas, habitat loss, climate change, and pollution
