Exam 4 Flashcards
(34 cards)
Identify synapomorphies of the Echinodermata
2nd Pentaradial Symmetry
Ambulacral zone: where tube feet pass through body
Loss of cerebral ganglia
CaCO3 endoskeleton
Hydrostatic system with madreporite and tube feet
Describe the transition in symmetry that Echinoderms undergo. Explain the adaptive significance of each kind of symmetry.
All Echinoderms have a pentaradial symmetry but they started out as bilateral larvae. Their larvae actually swim in the water to avoid predators, but as they grow they become slow/stationary and have to be able to see/feel from all directions.
Describe the unique connective tissues of echinoderms and how they can be adaptive.
Echinoderms have smart connective tissue that allows them to voluntarily separate their appendages (which they can regrow back). This allows them to escape their predators or hopefully satisfy their hunger enough to not eat the rest of the echinoderm.
Explain how Echinoderms deal with the major challenges that your skeleton deals with.
Essentially Echinoderms have all three skeletal types: Hydrostatic( they use water to move around), Exoskeleton (they have CaCO3 armour that protects), and an Endoskeleton plate (that gives them structure)
Describe the characteristics (synapomorphies) of each class of echinoderms.
Crinoidea (sea lillies)
- lack tube feet
- No Madreporite
- tube feet with suckers
- oral side down
Ophithuroidea (Brittle Star)
- no anus
- articulating appendages
- madreporite
- loss of suckers
Asteroidea (the common starfish)
- gonads and guts in arms
- pedicellirae
Echinoidea (sea urchins)
- Test
- Moveable spikes
- pedicellirae
- no arms
List the defining characteristics of chordates. Identify the subphyla.
All Chordates have: post-anal tail, notochord, dorsal hollow nerve chord
Urochordata: Sea Squirts, Salp, Tunicate
Cephalochordata: Lancelet
Craniata: hagfishes and vertebrates
Identify the traits that show how the hemichordates are related to echinoderms, and to chordates.
Echinoderms: They have similar larvae states and DNA sequences
Chordates: branchial openings, or “gill slits,” that open into the pharynx; there is a rudimentary structure in the collar region, the stomochord, that is similar to a notochord; and there is a dorsal nerve cord, in addition to a smaller ventral nerve cord
Explain the function of a lateral line system.
The lateral line system is a sense organ in fishes that allows them to detect movement and vibration via water pressure. This allows them to react quickly to predators and move as a group.
Explain the evolution of jaws.
During development, the 1st and 2nd-gill slits disappear, and the 3rd gill slit develops into the jaw while the 4th develops into jaw supports
Explain why shark scales are called denticulate.
Shark scales are made of dentine, so basically shark scales are little teeth.
Determine the sex of a shark or ray from a picture or specimen.
A male shark/ray have two reproductive organ call claspers that they use to inject sperm into the female reproductive opening called a cloaca
Explain the distribution and function of ampullae of Lorenzini.
The ampullae of Lorenzini are found on Elasmobranchii (such as shark, rays, and chimaeras). They are sensory canals and receptors that respond to weak electric fields, and possibly to temperature, water pressure, and salinity.
Compare and contrast the cartilaginous fishes and the ray-finned fishes.
cartilaginous fish: swim bladder absent, cartilaginous endoskeleton, internal fertilization, placciod scale
ray-finned fishes: swim bladder present, bony endoskeleton, external fertilization, cycloid scales
List characteristics that Tiktaalik has that are like tetrapods. List tetrapod traits that Tiktaalik lacks or is not known to have. Explain why Tiktaalik is such an important fossil.
Similarities: neck, wrist, flat head, eyes on top of head, snaps food
It is important because it’s the first species to have a pictorial girdle that allows it to crawl on land
Explain how amphibians are suited to life on land. Explain how they are still dependent on water.
Land: Doesn’t have scales, poison glands in skin for protection, powerful legs, claws, moist skin for gas exchange.
Dependent on Water: Eggs need water and larval stage requires aquatic environment.
Draw a diagram of the amniotic egg and explain the functions of each membrane.
Allantois: Waste disposal sac for metabolic waste produced by embryo; membrane functions with the chorion as respiratory organ.
Amnion protects the embryo in a fluid-filled cavity that cushions against shock. Chorion and allantois exchange gas between the embryo and the air; O2 and CO2 diffuse freely across shell. Yolk sac: Contains nutrients (yolk); blood vessels in this membrane transports nutrients into the embryo.
Explain the significance of the evolution of the amniotic egg.
The amniotic egg was an evolutionary invention that allowed the first reptiles to colonize dry land more than 300 million years ago. Fishes and amphibians must lay their eggs in water and therefore cannot live far from water. But thanks to the amniotic egg, reptiles can lay their eggs nearly anywhere on dry land.
List some defining characteristics of mammals.
Mammary glands, Hair, Three inner ear bones (malleus[hammer], incus[anvil], and stapes[stiruup]), sweat glands
Compare how many bones are present in the lower jaw of reptiles vs. the lower jaw of mammals.
Reptiles: larger angular, quadrate, and articular
Mammals: dentary is the only real part of the lower jaw
Explain the evolution of middle ear bones in mammals.
In mammals, a new joint formed beneath the dentary and quadrate and articular bones became incorporated into the middle ear as 2 of 3 bones that transmit sound from the ear drum to the inner ear.
Identify a feature of a mammalian skull that is evidence of high body temperature
Scroll-shaped bone in naval cavity. Brain case size, multiple holes in skull.
Identify two unique features of turtle skeletons.
Box-like shell with upper and lower shields fused to vertebrae, clavicles and ribs with horned beak, head retractable into skeletal system.
List characteristics of modern birds that suit them for flight.
- hand bones with attached feathers provides propulsion
- wing is streamlined with a concave lower surface
- The leading edge of the wing has small tight-fitting feathers.
Distinguish between saurischian and ornithischian dinosaurs by examining the pelvic bones. Identify which group was the most recent ancestor of birds.
Saurischian: Pelvic bone (pubis) points forward
Ornithischian: Pelvic bone points backwards
Saurischians are most related to birds, birds derived the trait later.
