Vertebrates Flashcards
What are the general characteristics of the phylum Chordates?
- Bilateral symmetry/triploblastic
- Coelomate
- Deuterostomes (anus first then mouth)
- complete digestive tract
- closed circulatory system
- most have endoskeleton
- Two groups of invertebrates, rest are vertebrates
What are the DEFINING characteristics of the phylum Chordata?
- notochord
- dorsal, hollow nerve cord
- pharyngeal slits or clefts
- post-anal tail
Humans are chordates, but they lack the defining characteristics of chordates because they were developed into something else, tell me what each of the 4 characteristics of chordates developed into in humans.
- Notochord was replaced by vertebrae
- Nerve cord developed into spinal cord
- pharyngeal slits formed eustachian tubes
- postanal tail is present as embryo but regresses
What are vertebrates?
Chordates with a backbone
What are gnathostomes?
Vertebrates with jaws (think gnom gnom gnom)
What are tetrapods?
Gnathostomes that have 4 limbs
What are amniotes?
Tetrapods that have terestrially adapted egg
What are mammals?
amniotes that have hair and produce milk
What are humans?
Mammals that have a large brain and bipedal locomotion.
Describe a lancelet (invertebrate)
Chordate
Named because of bladelike shape
Marine suspension feeder
Describe a Tunicate (invertebrate)
Chordate
closer related to chordates than lancelets
resemble chordates during larval stage, but lose characteristics in adulthood
Have incurrent and excurrent siphon that filter food in water
What are the defining characteristics of a vertebrate?
- Vertebral column replaces embryonic notocord
- Skull protects brain, high degree of cephalization
- Endoskeleton used for protection and muscle attachment
- Large coelom and internal organs, various body systems
Describe an agnathan (clade: cyclostoma).
Vertebrate
Jawless fish
cartilagenous skeleton
no scales or paired fins
What are two examples of an agnathan (vertebrate)
Hagfish - bottom-dwelling marine scavenger, have slime glands that secrete slime that covers gills and suffocates predators
Lampreys - parasites of live fish
Describe gnathostomes and what are the two clades we need to know?
“Jawed fishes”
2 Clades: Chondrichthyans and Osteichthyans
Describe the clade of chondrichthyans (gnathostomes).
Shark, stingray, ratfish
Cartilagenous fishes
uncovered gill slits
Go in depth on sharks (gnathostome: Chondrichthyan)
ampullae of lorenzini: detects electrical fields of nearby animal (for predation), located around the sharks nose
Most are predators, some of the largers ones are suspension feeders
Three ways embryos can develop (all internal) (will be described in another card)
have a cloaca - reproductive, excretory, and digestive tract all empty into common area
Describe the three ways a sharks embryo can develop.
Oviparous - Eggs hatch outside the mothers body
Ovoviviparous - embryo develops within the uterus and is nourished by the egg yolk
Viviparous - Embryo develops in the uterus and is nourished through a yolk sac placenta from the mothers blood
Describe osteichthyans (gnathostomes).
Bony fishes (and tetrapods)
gill slits covered with bone (operculum)
lateral line system - tactile sensory organ that detects movement and pressure changes in water
Swim bladder (needed because bone weighs fish down)
Oviparous - Lay eggs
What are the two types of osteichthyans (gnathostomes) we talked about in class?
Ray-finned fish - fin derived from skin, most fish are ray-finned (tuna, mudskipper, lionfish, seahorse, fine-spotted moray eel)
Lobe-finned fish - thick and fleshy fins supported by bones. Can swim and “walk” underwater. (coelacanths, lungfishes, tetrapods)
What is the huge thing that happened for vertebrates about 365 million years ago?
fins of some lobe-finned fish became limbs and feet of tetrapods.
What are the characteristics of a tetrapod?
- Four limbs and feet w/ digits
- Neck that allows head movement separate from body
- fusion of pelvic girdle to backbone
- absence of gills
- ears for detecting airborne sounds
What are the benefits to life on land?
Escape from aquatic predators
Access to new resources
What is the significance of Tiktaalik?
nicknamed fishopod
showed both fish and tetrapod characteristics, as well as a transition to life on land
What were the tetrapod and fish characteristics of Tiktaalik?
Fish: fins, gills and lungs, and fins
Tetrapod: Neck, ribs, fin skeleton, flat skull, eyes on top of skull
what are the three orders of amphibians (tetrapod)?
Urodela - have tails
Anura - no tails
Apoda - no legs
Describe Urodela (tetrapod: amphibian).
Salamanders and newts
Axolotl show paedomorphosis - the retention of juvenile features in sexually mature organisms
Describe Anurans (tetrapod: amphibian)?
Frogs
Lack tails and have powerful hind legs for locomotion on land
Frogs with leathery skin are toads
Describe Apoda (tetrapod: amphibians).
Resemble worms
absence of legs in secondary adaptation
nearly blind
Describe some of the features of amphibians.
Cutaneous breathing - skin aids lungs in gas exchange
Tadpoles: lack legs but eventually grow legs, lungs, ears, and predatory adaptations come during metamorphosis
How do amphibians fertilize eggs?
Outside of the body mostly, require a moist environment
In some species the male or females carry their eggs in their mouth, gut, or backs.
Why have amphibian populations been decreasing in recent decades?
a chytrid fungus causes disease that dries out skin and suffocates them.
What are the two types of amniotes (tetrapods w/ terrestrially adapted egg)?
Reptiles and mammals
What are the specific characteristics of amniotes?
- Amniotic (shelled) egg w/ 4 extraembryonic membranes
- embryos in eggs are bathed in fluids
- skin is rich in keratin, preventingit from drying out
- lungs throughout their life
- Kidneys conserve water
- Internal fertilization
What are the functions of the amnion, chorion, yolk sac, and allantois in an amniotic egg?
amnion - fluid filled cavity
chorion - gas exchange
yolk sac - nutrient and water storage
allantois - disposes metabolic wastes
Reptiles are ectothermic, meaning that absorbing external heat is how they raise their body temperature, this is why we see snakes and other reptiles “sunning”.
Endotherms are capable of maintaining their body temperature through their own metabolism.
WHAT ARE SOME ADVANTAGES AND DISADVANTAGES OF BOTH OF THESE MODES OF BODY TEMPERATURE REGULATION?
Advantages of ectothermy: do not need a constant food supply to drive metabolism and have simple control mechanisms for body heat
Disadvantages of ectothermy: cannot survive in a wide range of conditions (Winters for example).
Advantages of endothermy: Can survive in a wide range of conditions and habitats
Disadvantages of endothermy: must have a constant food supply to drive metabolism and have complex control mechanisms
What are the four orders of reptiles?
Chelonia (turtles and tortoises)
Rynchocephalia (tuataras)
Squamata (snakes and lizards)
Crocidilia (crocodiles and alligators)
Describe turtles.
Boxlike shell: upper shield (carapace) and lower shell (plastron) that is fused to the vertebrae, clavicles and ribs
Describe tuataras.
Lizard-like reptiles
Lepidosaurs (have scales)
LOCATED IN SMALL ISLANDS OFF NEW ZEALAND THREATENED BY INTRODUCED RATS THAT EAT THEIR EGGS
Describe snakes and lizards.
Lepidosaurs
Snakes evolved from lizards
Snakes are carnivorous and have:
- chemical sensors
- heat-detecting organs
- venom
- loosely articulated jawbones and elastic skin
Describe why Crocodilians are the closrest living relative to birds.
Closest living relatives to birds because:
- vocal
- parental behavior
- 4 - chambered heart (no mixing of 0-2 rich and 0-2 poor blood)
what are two types of crocodilians?
crocodiles and alligators
What are the key characteristics of birds (amniote)?
- Keratinized feathers that are derived from scales (help insulate, help w/ courting, flight, and to keep skin dry)
- They are lightweight: no bladder, no teeth, thin bones, females have one ovary
- lungs are connected to air sacs that store O2
- 4-chambered heart
- endothermic
- well-developed sense organs and nervous systems (acute vision)
- internal fertilization
- have cloaca
What are some benefits to flight?
enhance hunting and scavenging
escape terrestrial predators
migration
Where did birds descend from?
A small group of carnivorous dinosaurs
What are some of the groups of birds that are flightless?
ratites (ostrich, rhea, emu)
penguins
some species of rails, ducks, pigeons
What is the largest order of birds?
Passeriformes (perching birds)
What are the characteristics that describe mammals?
- mammary glands that produce milk
- hair
- endothermy - high metabolic rate
- larger brain that other vertebrates of similar size
- differentiated teeth
What are the three living lineages of mammals?
Prototherians (monotremes)
Metatherians (marsupials)
Eutherians (placentals)
Describe monotremes (prototherians) and give some examples of them, where are they native to?
- Lack mammary glands but mothers skin releases milk
- Lay eggs
echidnas (spiny anteaters) and platypus
Native to Australia and New Guinea
What is one way that a platypus (monotreme) fends off predators?
They release a toxin
Describe marsupials (metatherians), give some examples of them, and where are they native to?
- Embryo develops in placenta in mothers uterus, but, embryonic development is completed in a maternal pouch (marsupium).
- Kangaroos, koalas, and opossum
- Native to Australia and Americas
Describe Eutherians (placentals).
- young develop in mothers body, pregnancy lasts longer than marsupials
- embryo nourished by placenta (allows diffusion of substances between maternal and embryonic bloodstreams)
Only mammals to live in the sea and fly
Describe the O2 content of umbilical arteries/veins and maternal arteries/veins.
Umbilical vein - O2 rich
Umbilical artery - O2 poor blood
Maternal artery - O2 rich
Maternal vein - O2 poor
Describe convergent evolution as it relates to marsupials and eutherians, what is an example of this?
- Happens when unrelated organisms share a feature.
- Example: sugar glider (marsupial) and a flying squirrel (eutherian)
Are monotremes oviparous or viviparous?
What does this mean?
Do they have a vagina or cloaca? Uterus?
Do they have nipples or produce milk?
Oviparous
Meaning they lay eggs (no placenta)
cloaca and no uterus
No nipples but produce milk
Are marsupials oviparous or viviparous?
What does this mean?
Do they have a vagina or cloaca? Uterus?
Do they have nipples or produce milk?
vivparous
means they give live birth
means they have placenta (simple: has yolk)
vagina and uterus
nipples and milk
Are eutherians (placentals) oviparous or viviparous?
What does this mean?
Do they have a vagina or cloaca? Uterus?
Do they have nipples or produce milk?
vivparous
means they give live birth
means they have placenta (complex: tissues)
vagina and uterus
nipples and milk
With monotremes being oviparous (egg laying), what is the process they undergo to develop the yolk?
Vitellogenesis, which includes vitellogenin (VTG) proteins that are encoded by VIT genes.
Do all mammals have VIT (for vitellogenesis)? If so, why dont they all produce a yolk?
YES, however they are all inactive (pseudogenes) except for in monotremes
What are the defining characteristics of primates which are eutherians which are mammals?
- Have feet and adapted them for grasping, have flat nails
- large brain and short jaws
- forward-looking eyes close together on the face that help to provide depth perception
- complex social behavior and parental care
- fully opposable thumbs (monkeys and apes)
What are the three main groups of primates?
lemurs
tarsiers
monkeys & apes (anthropoids)
What is one main way to tell between a monkey and an ape?
monkeys have tails and apes do not
where did new world monkeys first appear?
South America
What are two main characteristics of New World monkeys?
they are arboreal (live in trees) and have a prehensile tail (can grasp)
Give an example of an OW and a NW monkey
OW - macaque
NW - spider monkey
Where are apes diverged from?
OW monkeys
What are some examples of apes?
gibbons, gorillas, chimpanzees, bonobos, and humans
What are some specific characteristics for humans?
- upright posture and bipedal locomotion
- larger brains that are capable of language, symbolic thought, artistic expression, and the manufacture and use of complex tools
- reduced jaw bones and jaw muscles
- shorter digestive tract
Which ape genome is 99% identical to humans? What does this tell us?
Chimpanzees
This tells us that changes in regulatory genes can have a large effect on the organism
What are the closest related group to humans other than chimpanzees?
Hominins
What is special about homo habilus?
These were the first handymen, earliest found “homo”, made stone tools
What is homo ergaster known for?
Decrease in sexual dimorphism (difference in size between gender)
Where did homo erectus migrate from?
Africa
What are some characteristics of homo neanderthalensis?
Lived in Europe
thicker bones
larger brains
made tools for hunting
buried their dead
What are the two hominins that homo sapiens (the only living hominin left, this is US) mated with?
neanderthalensis and erectus
we made tools and art, showed first signs of sophisticated thought
What is the advantage of bipedal locomotion?
it is more energy efficient than walking on all fours.
Where did homo spaiens originate from?
Africa
What are 2 common misconceptions about human evolution and the correction for them?
- Early hominins were chimpanzees
- Hominins and chimpanzees shared a common ancestor
- Human evolution is like a ladder leading directly to homo sapiens
- Hominin evolution included many branches or coexisting species, though only humans survive today
