Vertebrate Diversity

Question 1

Chordates

Answer 1

-Notochord
-Dorsal hollow nerve chord
-Pharyngeal slits
-Post anal tail

Question 2

Notochord

Answer 2

-Flexible, rod-shaped structure
-Located between the digestive tube and nerve cord
-Provides skeletal support throughout the length of the body
-In vertebrates, notochord is present during embryonic development, then it induces the development of the neural tube. Notochord is NOT found in the postnatal stage in vertebrates, it is replaced by the vertebral column.

Question 3

Dorsal Hollow Nerve Cord

Answer 3

-Lies within the ectoderm that rolls into a hollow tube during development
-In chordates, it is located dorsal to the notochord.
-In most chordates, the nerve cord eventually develops into the brain and spinal cord (the central nervous system).

Question 4

Pharyngeal Slits

Answer 4

-In aquatic organisms (i.e. fish), these slits allow for the exit of water that enters the mouth during feeding.
-In vertebrate fishes these slits are modified into gills, and in jawed fishes into jaws.
-In tetrapods the slits are modified into components of the ears and tonsils.

Question 5

Post Anal Tail

Answer 5

-Posterior elongation of the body, extending beyond the anus.
-Tail contains skeletal structures and muscles
-In aquatic organisms the adult form maintains this structure to aid in locomotion.
-In some terrestrial vertebrates, tails can help with balance, courting, and signaling.
-In humans, the post-anal tail is a vestigial structure

Question 6

Urochordata

Answer 6

-Tunicates
-Tunic covering composed of cellulose-like carbohydrate material
-Adult form does not have notochord, dorsal hollow nerve cord, or post-anal tail, but the larval stage does
-Pharyngeal slits in both larval and adult stages

Question 7

Cephalochordata

Answer 7

-Possess all of the chordate characteristics in the adult form (as well as the embryonic form).
-The notochord extends into the head (why it is named cephalochordata).
-Extant members are the lancelets, named for their blade-like shape.
-Small, only a few cm long
-Usually live buried in sand at the bottom of warm temperate and tropical seas
-Are filter feeders

Question 8

Extant

Answer 8

Living

Question 9

Craniata

Answer 9

-A group of organisms that have a cranium (bony, cartilaginous, or fibrous structure surrounding the brain), jaw, and facial bones.
-Most are bilaterally symmetrical
-This group includes the hagfishes, which have a cranium, but lack a backbone and ALL of the vertebrates

Question 10

Vertebrates

Answer 10

Display all four characteristics of chordates, but they also have a vertebral column composed of cartilage and bone and is derived from the notochord (only present in the embryonic stage) during development.

Molecular evidence and fossil evidence suggests that vertebrates are more closely related to lancelets than tunicates.

Question 11

Fish

Answer 11

Categorized into jawless fishes and jawed fishes

Jawless fishes
Hagfishes – eel-like scavengers live on the ocean floor and are detritivores
Not ‘true vertebrates’ – the notochord fails to completely develop into a vertebral column
Lampreys – similar to hagfishes in size/shape; but possess a vertebral column, many are ectoparasites

Jawed Fishes
Possess sets of paired fins, the evolution of a jaw allows the expansion of food sources, and likely the reason jawed fishes replaced many species of jawless fishes during the Devonian Period.
Most belong to either the Condrichthyes and Osteichtyes groups.

Question 12

Chondrichthyes: Cartilaginous fish

Answer 12

-Have skeletons made of cartilage.
-Live mostly in marine habitats (although some freshwater species exist).
-Include sharks, rays, and skates.
-Most are Oviparous (mother births a fertilized egg, which hatches external to her body), some Viviparous (live birth)

Question 13

Osteichthyes: Bony fish

Answer 13

-Have skeletons made of bones.
-Have a swim bladder to assist with buoyancy control.
-Species have evolved to be marine or freshwater, some can do both or live in brackish water (but its rare)
-Ex: Mahi Mahi, Queen Angelfish, Trout

Question 14

Amphibians

Answer 14

-Tetrapod – evolved limbs for weight support
-Cutaneous respiration – oxygens/carbon dioxide exchange that can happen through the skin
-Internal fertilizers

Question 15

Reptiles

Answer 15

-Like many amphibians, most reptiles are tetrapods, although some limbless reptiles exist (i.e. snakes)
-Reptiles lay eggs enclosed in shells on land
-Some are ovoviviparous (mother incubates eggs internal, births eggs very close to hatching) or Viviparous (live birth).
-Originated about 300 million years ago during the Carboniferous Period
-Dinosaurs were reptiles and make up the dominant terrestrial animals until their extinction
-Extant groups include: crocodiles, turtles, snakes, and lizards

Question 16

Birds

Answer 16

-Have evolved pneumatic bones (hollow bones) to reduce weight
-Feathers to direct airflow providing lift and thrust required for flight
-Lack urinary bladder to also reduce weight – water is reabsorbed in the cloaca, urinary waste is passed on as a solid along with fecal matter
-Most bird species have females with only one ovary to reduce weight
-Air only flows in one direction, creating a cross-current exchange system with the blood, which increases gas exchange efficiency

Question 17

Mammals

Answer 17

-Important characteristics are: sebaceous skin, hair, one single lower jaw, heterodont teeth (many different shapes/sizes), four-chambered heart, produce milk to nurse young, and internal gestation with live birth (viviparous).
-Exception to the last characteristic: monotremes (i.e. platypus) – lay eggs rather than give live birth

Main groups:
Monotremes
Marsupials (characterized by giving live birth, but continued development in an external pouch)
Eutherian mammals (placental mammals) – have internal development with a placental structure for nutrients/gas exchange

Question 18

Primates

Answer 18

-Rotating shoulder joint
-Big toe separated from other toes and thumbs, which are widely separated from fingers (except humans)
-Stereoscopic vision – two overlapping fields of vision from the eyes – allows for depth perception and gauging distance
-Brains are larger than other mammals
-Claws modified into flattened nails
-Typically only one offspring per pregnancy – large amount of parental care required
-Only one species of complete upright walkers is currently living (humans) – although others existed previously

Question 19

Cutaneous respiration

Answer 19

Oxygens/carbon dioxide exchange that can happen through the skin

Question 20

Viviparous

Answer 20

Live birth

Question 21

Ovoviviparous

Answer 21

Mother incubates eggs internally, births eggs very close to hatching

Question 22

Oviparous

Answer 22

Mother births a fertilized egg, which hatches external to her body

Question 23

Instinct

Answer 23

Adaptation occurs over generations by selection that results in the various behaviors we observe

Question 24

Learning

Answer 24

Behaviors are the result of each individual animal’s unique life experiences.

Question 25

What are the advantages to grouping?

Answer 25

-Protection from predators
-Protection from extreme environments/assistance with homeostasis
-Assistance with food acquisition

Question 26

What are the disadvantages to grouping?

Answer 26

-Increased competition for food
-Increased risk of disease transmission
-Greater conspicuousness to predators
-Cuckoldry (cheating)
-Cannibalism of young

Question 27

Epigenetics

Answer 27

When gene expression is altered due to other gene expression in the genome or environmental factors

Question 28

Eusociality

Answer 28

Live in large groups with individuals assigned to specific roles or castes, like queen, drone, and worker. Queens produce sterile female workers. Ex: Kin selection, exhibit higher levels of altruism because of genetic similarity

Question 29

Kin Selection

Answer 29

The lowering of individual fitness to enhance the reproductive fitness of a relative and thus one’s inclusive fitness evolves through kin selection.