Lecture 17: Vertebrates Flashcards
Vertebrates
- Development of a skeletal system and more complex nervous system
- Better ability to chase prey and run from predators
Most vertebrates have vertebrae that enclose the
spinal cord
* Replaces the mechanical roles of the notochord
Early-diverged vertebra
- No jaws
- Cartilage skeleton, composed of extracellular matrix proteins like collagen
- Cartilage can be mineralized with calcium for added support
Gnathostomes: Ancient Greek, gnathos-stoma, ‘jaw-mouth’
- Cartilage fish (sharks, rays, etc.)
- One of the biggest and most successful vertebrate predators in oceans
- Predominantly cartilage skeleton
- Limited use of mineralization may be a ‘derived trait’ for these species, as mineralization was present before they diverged from other vertebrates
Jaws
hinged structures that enable
animals to grip food items / slice them
Ray-finned fishes
- Fins are made of bony rays connected with webs without muscular structure
- Most of the extant ‘fish’ species are ray-finned
Lobe-fin fishes
- Pectoral and pelvic fins have a thick muscle
supporting the bony fin - Muscular fins can be used to walk on the bottom of the water
- Not a lot of extant species (with exception)
Ray-finned fishes and lobe-finned fishes skeleton and skeletal composition
Nearly all have ossified (bony) endoskeleton with a hard matrix of calcium phosphate
Three major groups of Lobe-fin fishes
Coelacanths
Lung fish
Tetrapods
Coelacanths definition
(pronounced SEE-le-kanth): The ‘living fossil’ that is believed to have remained unchanged from its ancestral shape for ~400 million years
Lung fish definition
Fish who has lungs as the means for gas exchange (in addition to gills)
Tetrapods definiton
Sister group of lung fish who adapted to life on land
* Muscular, pectoral and pelvic fins of lobe-fin fishes evolved into limbs with digits
Tetrapods structure and evolutionary timeline
- Tetrapods are Gnathostomes that have limbs with digits
- Greek,”four feet”
- Diverged about 365 million years ago
- Limbs support animal’s weight on land while digits efficiently transmit forces to the ground when walking
- Limbs changing into hands, wings and flippers
Amphibians
- Salamanders, frogs, caecilians
- Amphibian (‘both ways of life) refers to the dual life stages of frogs
- Tadpole: Aquatic larval stage, herbivore, legless, tail, gills
- Frog: Terrestrial adult stage, carnivore, legs, tailless, lungs
Many amphibians are strictly __ or __
aquatic, terrestrial
* Still need to inhabit moist habitat
* Major gas exchange through skin
* Lays egg in moist environment or in water; eggs are not well protected from desiccation
Amniotes
- Amniotes are tetrapods with terrestrially adapted eggs
- Reptiles and mammals
Amniotic egg contains
specialized membranes to nurture the embryo
* Amnion is the membrane that encloses the amniotic fluid which the embryo floats in
* Other membranes function in gas exchange, transfer of nutrients, waste storage
Amniotic egg allows terrestrial organisms to
nurture embryo without having access to a body of water
Reptiles
Turtles, tuataras, lizards, snakes, crocodilians, birds
Many reptiles such as lizards and snakes are
ectothermic
* ‘Cold blooded’
* Use the environment (sun/shade)to
regulate their body temperature
* Need tenth of the energy to survive compared to a mammal of the same size
Birds are
endothermic
* Uses metabolic activity to maintain body
temperature
* Less energy efficient but resilient to harsher environments
Mammals
Mammals are Amniotes that have hair and produce milk to nurture the young
Milk
balanced diet rich in fats, sugars, proteins, minerals and vitamins
* Produced in mammary glands
Mammals are __ with high metabolic rate
endothermic
* Hair and fat layer under the skin provides insulation
Mammals have a ___ for body size
larger brain
* Allows complex learning behavior such as offspring learning skills from parents (knowledge transfer, not just ‘learning’)
Three mammalian types
- Monotremes
- Marsupials
- Eutherians (placental mammals)
Monotremes are found only in
Australia and New Guinea
* Platypus and echidnas
* Lays eggs, as with other non- mammalian amniotes
Marsupials
- Opossums, kangaroos, koalas, etc.
- Embryo develops inside the female body, nurtured by the placenta
- Child born very early in development and gets nourished in the mother’s pouch
Most extant marsupials are in the
Australian region
* Opossum are the few marsupial species that still survive in North/central America
* Convergent evolution have given rise to many marsupials which look similar to placentals that occupy similar ecological niches
Eutherians (placental mammals)
- Have placenta that are more complex than marsupials
- Longer pregnancy
- Young eutherians complete their embryonic
development within the uterus
Eutherians (placental mammals) life forms and habitats
- Various life forms and habitats
- Wide range of food, meat, nuts, grass, insects, etc.
Teeth variety observed in Mammals
- Teeth of mammals bear a variety of sizes and shapes adapted for chewing many kinds of foods
- This type of variety is observed mainly in mammals, and is one reason for their success
Carnivore digestive tract
- Large, expandable stomachs are common on carnivorous vertebrates
- Need to eat large when they can, long intervals between feeding
Herbivore & Omnivore digestive tract
- Herbivores and omnivores have longer alimentary canals relative to body size, as compared to carnivores
- Vegetation is more difficult to digest rather than meat because of cell walls
- Longer digestive tract furnishes more time for digestion and more surface area for absorption of nutrients
Gut microbiome
we co-exist with beneficial microbes living in our intestine
Mutualistic gut microbiome is especially important in
herbivores
* Vertebrates cannot digest cellulose cell wall of plants to convert it to energy
How do Herbivores digest the cellulose cell wall?
Many herbivores host various mutualistic bacteria and protists in fermentation chambers of their alimentary canals
* These microorganisms digest cellulose to simple sugars that the animal can absorb
Three main groups of primates
- Lemurs, lorises and bush babies
- Tarsiers
- Anthropoids: monkeys, apes
Primates
- Earliest known primates were tree dwellers
- All primates have thumbs that is separate from other fingers to easily grasp branches
All monkeys and apes have fully
opposable thumb
* Can touch the ventral (fingerprint) side of all four fingers with the ventral surface of thumb
(🤌)
Traits observed in Primates
- Eyes on one side of the face (overlapping vision) which gives better depth of perception
- Large brain, short jaws, flat face
- Well developed parental care and complex social behaviour
Species of Apes
- Gibbons (Hylobates sp.)
- Orangutans (Pongo sp.)
- Gorilla (Gorilla sp.)
- Chimpanzees and bonobos (Pan sp.)
- Humans (Homo sp.)
Shared traits for Apes
- Usually larger than monkeys
- No tail
- Only gibbons and orangutans are
primary arboreal (lives on trees)
What trait is not yet seen in Apes
No bipedal locomotion yet
Hominins
extinct species which are more closely related to humans than to other apes
___ seen in early hominins (since ~6.5 million years ago)
Bipedal locomotion
Multiple lineages of __ existed throughout the history of evolution
bipedal hominins
We (Homo sapiens) are the __ which survived; others are extinct
only hominin lineage
__ may have evolved after bipedal locomotion
Use of tools
Evidence fours of tools and observed in which species
- Evidences show hominins cutting flesh from the bones of animals
- Other non-hominin apes can use tools too
- Orangutans putting sticks into holes to fish food, etc.
The genus Homo
- Early Homo all spread from Africa into Europe/Asian regions as they diversified
- Homo habilis, 2.4–1.6 million years ago
- Homo ergaster, 1.9–1.5 million years ago
Neanderthals (Homo neanderthalensis)
- Burying their dead
- Hunting tools from stone and wood
- Extinct 28000-40000 years ago
Neanderthals is a different lineage as compared to humans, but ___
but some gene flow did exist between the two species via inbreeding
Homo sapiens (Human)
- About 200000 years old (0.2 million
years) - Bipedal locomotion
- Language, symbolic thought, artistic expression, manufacture and use of complex tools
- Reduced jawbone, jaw muscles, shorter digestive tract
