Bio II Lecture 15 (Intro to Chordates)

What are the chordates?

coelomate, bilateral animals

what are the four key characteristics of the chordates?

1. presence of a notochord

2. nerve chord runs parallel with notochord and gut

3. gill slits penetrate the wall of a pharynx (at some point in development)

4. tail extends past arms (at some point in development)

what is a notochord?

rod of stiffened, but flexible tissue that supports and gives structure

what does the anterior end of the nerve cord develop into?

the brain (CNS)

what are the three parts of the brain in a tripartite brain?

cerebrum, cerebellum, medulla

what is the cerebrum, and what does it allow?

forebrain, allows for cognitive function

what is the cerebellum, and what does it allow?

back part of brain, allows for equilibrium and balance

what is the medulla, and what does it allow?

brain stem, allows for homeostatic physiological rhythm in body

what are the three major sub-phyla within the chordates?

Urochordata, Cephalochordata, Vertebrata

What is the most ancestral group of chordates?

urochordata

What are urochordates?

tunicates, sea squirts

the urochordates are the only group that lack a _________.

vertebrate

the urochordata can be both _______ and ________ .

sessile, mobile

adults are the ______ form, and the larvae are ______.

sessile, mobile

what type of feeders are urochordata?

filter feeders

what are the three structures that allow for filter feeding?

incurrent siphon, excurrent siphon, and gill slits

urochordates can be found in _______ habitats.

aquatic

what is the evolution of the pharynx's functions in the urochordata?

it has been used to aid in digestion, but it now aids in respiration as well

what sub phylum do the lancelets belong in?

cephalochordata

the cephalochordata have a ________ instead of a vertebrate

notochord

what are myomeres in cephalochordata?

defined muscle segments

How do cephalochordates feed?

filter feeding

what are the vertebrata?

chordates with a backbone

what is the function of the pharynx in the vertebrata?

respiration (gas exchange)

the vertebrata have accessory _______ ________.

digestive organs

the vertebrata also have a _________ heart.

chambered

how many chambers within the heart can the vertebrata have?

2-4

what is hemoglobin?

protein in red blood cells that has an affinity for oxygen

vertebrata have a ______ brain.

tripartite

what are the kidneys composed of?

nephrons

the system that regulates hormones throughout the body of the vertebrata is called the ________ system.

endocrine

what are the two major classes within the vertebrata discussed in class?

myxini and petromyzontida

what are the myxini?

hagfish

the myxini are the only class of vertebrates without a true ________, they instead have a ________.

vertebrate, notochord

the myxini are the first group with a ________.

cranium

what is the special adaptation of the hagfish in regards to their defense?

their body is lined with mucus glands that produce slime when activated, which can slow and deter predators

What class do lampreys belong to?

Petromyzontida

lampreys are the most _______ fish.

ancestral

lampreys are the first true ___________.

vertebrates

lampreys have a small _________ present.

cerebellum

what structures work with the cerebellum to balance?

two pairs of semicircular canals

true of false: lampreys are parasitic

true

what are the larvae of lampreys called?

ammocoetes

how do the lampreys kill fish, and what makes them a harmful, invasive species?

they clamp down on alive fish and kill them, which economically ruins the seafood industry because it makes the fish inedible

what are some conservation efforts used to control the lamprey population?

1. lamproite to kill larva

2. sterilization and release of males to prevent reproduction