Marine Bio: Early Chordates and Jawless Fish

Acorn worms are in the phylum \___.

Hemichordata

Phylum Hemichordata has an anterior tube, or \___.

stomochord

Acorn worms are found in \___ \___.

mud flats

There are 49,000+ species in Phylum \___.

Chordata

1,400 species are invertebrates (\___ and \___.)

tunicates and lancelets

Chordates have some type of "\___."

chord

Chordates have gills or \___ slits.

pharyngeal

Chordates have a \___ tail.

postanal

The "chord" Is part of the \___ \___ system.

central nervous

The anterior end of the chord is the \___.

brain

A notochord is a stiff but flexible rod of cells that run along the \___ nerve cord.

dorsal

A notochord is found in \___ chordates.

invertebrate

Vertebrate chordates have a vertebral column (\___ and \___.)

backbone and spine

In vertebrate chordates, a notochord is only present in the \___ stage.

embryonic

The notochord \___ to bones (vertebra) and surrounds nerve cord.

ossifies

Only segments of the notochord remain between vertebral \___.

disks

Phylum Chordata has a postanal tail, which is \___ in humans.

vestigial

The postanal tail is used for \___ \___ in aquatic organisms.

increased movement

Invertebrate chordates are also known as \___.

protochordates

Subphylum Urochordata includes \___ and \___.

tunicates and salps

Subphylum Cephalochordata includes \___.

lancelets

Subphylum Vertebrata has \___ surrounding the dorsal nerve cord.

vertebrae

Subphylum Vertebrata has a \___, or skull.

cranium

Subphylum Vertebrata has a(n) \___ — cartilage or bone.

endoskeleton

Jawless fish are in Class \___.

Agnatha

Class Agnatha includes \___ and \___.

hagfish and lampreys

Hagfishes are also known as \___ \___.

slime eels

Hagfish are in Order \___.

Myxiniform

There are __ known species of hagfishes.

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Hagfish are found in \___, \___ waters.

deep, cold

Hagfish's skin is used for \___ goods.

leather

Hagfish tie themselves into \___ in order to shed their slime coat and make a new one.

knots

Lampreys are in Order \___.

Petromyzontiform

Lampreys are \___.

parasitic

Lampreys use \___ to attach to fish.

suckers

Lampreys are found in \___.

freshwater

There are __ species of lampreys.

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