Chordates

Chordates have five characteristic features: ________, dorsal hollow nerve cord, pharyngeal slits, endostyle, and post

anal tail.

The ________ is a flexible rod

like structure extending the length of the body and functions as a hydrostatic organ.

The notochord is the first part of the ________ to appear in the embryo.

endoskeleton

The notochord provides an axis for ________ attachment.

muscle

The notochord bends without shortening, permitting ________ body movement.

undulatory

The notochord remains throughout life in primitive chordates but is replaced by ________ in most chordates.

vertebrae

The chordate ________ nerve cord is always dorsal to the GI tract and initially tubular (hollow).

dorsal

The anterior end of the dorsal nerve cord is enlarged to form the ________ in most chordates.

brain

In vertebrates, the nerve cord passes through protective ________ arches of the vertebrae.

neural

In craniates, the brain is enclosed by a protective bony or cartilaginous ________.

cranium

Chordate pharyngeal ________ lead from the pharyngeal cavity to the outside.

slits

Pharyngeal grooves/clefts are formed by inpocketing of the ________.

ectoderm

Pharyngeal pouches are formed by outpocketing of the ________ lining of the pharynx.

endodermal

The ________ secretes mucus that traps food particles in the pharyngeal cavity.

endostyle

The endostyle is considered the precursor of the ________ gland in lamprey and vertebrates.

thyroid

The chordate ________ tail evolved for propulsion in water.

post

The efficiency of the post

anal tail was later increased with the addition of ________ in fishes.

Urochordates are also called ________.

Tunicata

Only the ________ form of urochordates bears all five chordate hallmarks.

larval

Urochordates are all ________, and adults are generally sessile.

marine

Urochordates have a protective ________ (tunic) covering the body.

test

Urochordates are ________, with external fertilization.

hermaphroditic

Most urochordates are ________ feeders.

filter

The prominent oral ________ is the incurrent siphon in urochordates.

siphon

The dorsal atrial ________ is the excurrent siphon in urochordates.

siphon

The urochordate pharynx is a ________

like structure surrounded by an atrium except along the midventral line.

Water is drawn into the urochordate pharynx by ________ action.

ciliary

Water passes through the pharyngeal slits, called ________ in urochordates.

stigmata

The urochordate ________ runs the length of the midventral line.

endostyle

The urochordate endostyle secretes mucous ________ that trap food.

nets

The mucus nets converge on the dorsal side, where the mucus is rolled into a cord and passed posterior to the ________.

esophagus

The urochordate ascidian tadpole

like larva possesses all five chordate characteristics, including the ________, post

Cephalochordates are commonly called ________.

lancelets

The cephalochordate genus is ________ (former Amphioxus).

Branchiostoma

Lancelets are slender, laterally flattened, ________ animals about 5–7 cm long.

translucent

Lancelets live in ________ bottoms of coastal waters.

sandy

The lancelet ________ resembles