BI158 - Chapter 34: Origin and Evolution of Invertebrates

Chordates have a _________ and a dorsal, hollow, _______ _________.

notochord; nerve chord

chordates

an animal phylum that has a notochord, a dorsal hollow nerve cord, and gill slits at some time in its life cycle

notochord

a longitudinal, flexible rod located between the digestive tube and the nerve cord

pharyngeal clefts/slits

grooves in the pharynx that develop into slits that open to the outside of the body

The digestive tube of chordates extend from the _______ to the _______.

mouth; anus

lancelets

the most basal group of chordates that are blade-shaped and lack a backbone

tunicates

members of the subphylum Urochordata, sessile marine chordates that lack a backbone

sessile

an organism that does not move and remains attached to one place

Identify four derived characters that all chordates have at some point during their life.

nerve cord, notochord, post-anal tail, pharyngeal slits

What two animals are the only lineages of living vertebrates whose members lack jaws?

lampreys (Myxini) and hagfishes (Petromyzontida)

cyclostomes

jawless vertebrates

conodonts

a group of slender,

soft-bodied vertebrates that lacked jaws and whose internal skeleton was composed of cartilage

gnathosomes

jawed vertebrates

What animals include gnathostomes?

Sharks, ray-finned fishes, lobe-finned fishes, amphibians, reptiles, birds, and mammals

lateral line system

organs that form a row along each side of the body and are sensitive to vibrations in the surrounding water

placoderms

earliest gnathostomes in the fossil record that are an extinct lineage of armored vertebrates

acanthodians

another group of jawed vertebrates that radiated during the Silurian and Devonian periods

chondrichthyans

vertebrates with skeletons made mostly of cartilage, such as sharks and rays

ovoviviparous

term used to refer to animals whose young are born alive after developing in eggs inside the mother's body

viviparous

producing living young (not eggs)

cloaca

a common chamber that has a single opening to the outside

osteichthyans

member of a vertebrate clade with jaws and mostly bony skeletons

operculum

a protective flap that covers the gills of fishes

ray-finned fishes

bony fishes, including trout, bass, perch, and tuna. their fins are supported by thin, flexible skeletal rays

lobe-finned fishes

fish species characterized by two pairs of sturdy lobe-shaped fins on the underside of the body

Describe key adaptations of aquatic gnathostomes.

1. jaws

2. paired fins and tail for swimming

3. streamlined bodies

4. swim bladder/oily liver

What derived characters do sharks and tuna share?

they are gnathostomes and have jaws

What features distinguish tuna from sharks?

shark skeletons are made of cartilage while tunas have bony skeletons

tetrapods

vertebrate animals having four feet, legs or leglike appendages

__________ are gnathostomes that have limbs.

Tetrapods

Describe key adaptations of aquatic gnastosomes.

amphibians

vertebrates that live in water and on land, smooth skin covers body, lay eggs, cold blooded

Describe the origin of tetrapods and identify some of

their key derived traits.

Tetrapods originated from lobe-finned fish. Key traits: limbs with digits, lungs, strong bony skeleton, and modified hearing structures.

amniotes

a group of tetrapods whose extant members are the reptiles and mammals

amniotic egg

a shelled, water-retaining egg that enables reptiles, birds, and egg-laying mammals to complete their life cycles on dry land

What are the four specialized membranes of an amniotic egg?

the amnion, the chorion, the yolk sac, and the allantois

reptile

a vertebrate with scaly skin that lays eggs with tough, leathery shells

What are animals include reptiles?

tuataras, lizards, snakes, turtles, crocodilians, and birds

ectothermic

used to refer to animals that absorb external heat as their main source of body heat

enodothermic

used to refer to animals that are capable of maintaing body temperature through metabolic activity

parareptiles

large, stocky, quadrupedal herbivores

diapsids

reptiles possessing a skull with two pairs of openings behind each eye socket

What are the two lineages that diverged from diapsids?

lepidosaurs and archosaurs

lepidosaurs

tuataras, lizards, snakes

archosaurs

crocodilians, pterosaurs, and dinosaurs

pterosaurs

flying reptiles

dinosaurs

an extremely diverse group of ancient reptiles varying in body shape, size, and habitat

theropods

bipedal carnivores

Describe three key amniote adaptations for life on land.

amniotic egg to prevent desiccation, waterproof skin to reduce water loss, efficient lungs for gas exchange.

mammals

animals that have hair and produce milk for their young

synapsids

a group of amniotes in which mammals belong to

monotremes

mammals that lay eggs

marsupials

pouched mammals

placenta

organ that nourishes the fetus

eutherians

placental mammals

anthrpoids

a higher primate

Chordates are not _____________.

vertebrates

List some functions of pharyngeal slits.

suspension feeding, gas exchange, and development into parts of the ear, head and neck in tetrapods