vertebrates Flashcards
The animals called _______ get their name from vertebrae, the series of bones that make up the backbone
chordates w a backbone
vertebrates
-are bilaterian animals that belong to the clade of animals known as Deuterostomia
-include all vertebrates and 2 groups of invertebrates: urochordates and cephalochordates
chordates
four key characters of chordates
-notochord
-dorsal, hollow nerve cord
-pharyngeal slit or clefts
-muscular, post anal tail
-is a longitudinal, flexible rod between the digestive tube and nerve cord
-provide skeletal support thru out most length of chordate
notochord
-nerve cord of a chordate embryo develops from a plate of ectoderm that rolls into a tube dorsal to the cotochord
dorsal, hollow nerve cord
functions of pharyngeal slits
-suspension-feeding structure in many invertebrate chordate
-gas exchange in vertebrates (except vertebrates w limbs, the tetrapods)
develop into parts of the ear, head, and neck in tetrapods
grooves in the pharynx that develop into slits that open to the outside of the body
pharyngeal clefts
-tail posterior to the anus
-contains skeletal elements and muscles
-provides propelling force in many aquatic species
muscular, post anal tail
-named for their bladelike shape
-marine suspension feeders that retain characteristics of the chordate body plan as adults
lancelets (cephalochordata)
-more closely related to other chordates than are lancelets
-most resemble chordates during larval stage- last only a minute
-draws in water thru an incurrent siphon, filtering food particles
-when attacked, they choot water thru excurrent siphon
tunicates (urochordata)
sequencing of the tunicates genome indicates that
-genes associated with the heart and thyroid are common to all chordate
-genes associated w transmission of nerve impulses are unique to vertebrates
a skeletal system and complex nervous system have allowed vertebrates efficiency at two essential tasks
-capturing food
-evading predators
-fossil evidence show that earliest vertebrates lacked jaws
-2 lineages of jawless vertebrates remain today: _______ and ________
-members of these group lack backbone
-presence of rudimentary vertebrae and result of phylogenetic analysis indicate the both are vertebrates
hagfishes, lampreys
vertebrates have the ff derived characteristics
-vertebrae enclosing a spinal cord
-elaborate skull
-fin rays, in aquatic form
hagfishes and lampreys form a clade of living jawless vertebrates
cyclostomes
vertebrates with jaws make up much larger clade
gnathostomes
-are jawless vertebrates that have a cartilaginous skull, reduce vertebrate, and a flexible rod of cartilage derived from the notochord
-have small brain, eyes, ears, and tooth-like formations
-BOTTOM DWELLING SCAVENGERS
hagfishes
-parasites that feed by clamping their mouth onto a live fish
-inhabit various marine and freshwater habitats
-have cartilaginous segments surrounding the notochord and arching partly over the nerve cord
lampreys
-fossils from Cambrian explosion document the transition to craniates
-most primitive of the fossils are those of the 3-cm-long
-had a well formed brain, eyes, and muscular segments, but no skull or ear organs
haikouella
-vertebrates that have jaws
-include sharks, ray finned fishes, lobe finned fishes, amphibians, reptiles, and mammals
gnathostomes
-were among the earliest vertebrates in the fossil record, dating from 500 to 200 million years ago
-had mineralized skeletal elements in their mouth and pharynx
-fossilized dental elements are common in the fossil record
conodonts
derived characters of gnathostomes
-“jaw mouth”
-named after for their jaws, higned structures that, especially w the help of teeth, used to grip food items firmly and slice them
-jaws are hypothesized to have evolved by modification of skeletal rods that supported the pharyngeal (gill) slits
-enlarged forebrain associated w enhanced smell and vision
earliest gnathostomes in the fossil record are an extinct lineage of armored vertebrates
placoderms
-have streamlined body and are swift swimmers suspension feeders, but most are carnivores
-have short digestive tract w a ridge called spiral valve to increase digestive surface area
-have acute sense including sight, smell, and the ability to detect electrical fields from nearby animals
sharks
-another group of jawed vertebrates, radiated during Silurian and Devonian periods
acanthodians
-have skeleton composed primarily of cartilage
-largest and most diverse groups of this includes sharks, rays, and skates
chondrichthyans
eggs that hatch outside the mother’s body
oviparous
embryo develops w/in the uterus and is nourished by the egg yolk
ovoviviparous
reproductive tract, excretory system, and digestive tract empty into a common
cloaca
embryo develops w/in the uterus and is nourished through a yolk sac placenta from the mother’s blood
viviparous
-vast majority of vertebrates belong to a clade of gnathostomes called
-have a bony endoskeleton
-include the bony fishes and tetrapods
-fishes are the aquatic ones
osteichythyans
-include nearly all the familiar aquatic ostheichthyans
-fins supported mainly by long, flexible rays, are modified for maneuvering, defense, and other functions
-industrial scale fishing operations have driven the population to collpase. Ex. cod, blue fin tuna
-populations also affected by dams that change water flow patterns, affecting prey capture: salmon
ray finned fishes
-control their buoyancy w an air sac known as a swim bladder
-have a lateral line system
most species are oviparous, but some have internal fertilization and birthing
fishes
most fiches breathe during water over gills protected by an
opercullum
-have muscular pelvic and pectoral fins that they use to swim and “walk” underwater across the substrate
-three lineages survive and include coelacanths, lungfishes, and tetrapods
lobe fins
derived characters of tetrapods
-4 limbs and feet with digits
-a neck, which allows separate movement of the head
-fusion of the pelvic girdle to the backbone
-the absence of gills
Tiktaalik, nicknamed a “fishapod” shows both fish and tetrapod characteristics. it had…
-fins, gills, lungs, and scales
-ribs to breathe air and support its body
-neck and shoulders
-fins w the bone pattern of a tetrapod limb
