Lab 4

Question 1

Describe pharyngotremy, a feeding characteristic of protochordates

Answer 1

“pharyngotremy” is the perforation of
the pharyngeal walls by “gill-slits” through which a current of water is drawn

Question 2

Describe Petromyzons

Answer 2

Petromyzons are parasitic Agnathans. Their endoskeleton
has fibers and cartilage, and the notochord remains
throughout their life. They do not have scales or paired fins.
The mouth has epidermal teeth.

Question 3

Describe Amphibians

Answer 3

Amphibians are bony vertebrates and tetrapods (most have four pentadactyl limbs) and
are partly terrestrial. The free-living aquatic larval stage (tadpoles) breathe using gills, have
two-chambered hearts [like fish] and are limbless.

Question 4

Describe Chondrichthyes

Answer 4

Chondrichthyes are Gnathostomes which have an entirely cartilaginous endoskeleton, gill
slits (branchial arches), leathery skin and covered with tooth-like placoid scales (denticles),
heterocercal tail fin (the vertebral column
turns upward into the larger fin lobe),
cloaca (one common chamber for
intestinal, urinary, and genital openings),
spiral valve, and a heart with two
chambers.

Question 5

Explain The Developmental features shared by echinoderms

Answer 5

Layers: Triploblastic – 3 cellular layers
(endoderm, mesoderm, ectoderm)

Cavities: Eucoelomate (Coleum with mesoderm)

Embryonic development: Deuterostome
(mouth formed second; radial cleavage)

Symmetry: bilateral larvae; pentaradial adults

Segmentation: Non-segmented

Question 6

What are the Unique Echinoderm features?

Answer 6

Bilateral to radial metamorphosis with 90 degree
orientation of body axis

Adults radial but free-moving
Hydraulic water-vascular system (coelomic)

Dermal ossicles (and spines) secreted by sclerocytes

Question 7

What are general Echinodermata features?

Answer 7

– Complete gut except where
secondarily lost

– Spines

– Calcareous internal skeleton
– Simple Reproductive Systems – Diffuse Nervous System

Phylum Echinodermata

lacking specialized excretory
structures. –

lacking osmoregulation.

lacking specialized
respiratory structures in most

– lacking head or brain

-lacking heart

Question 8

What are Pedicellariae?

Answer 8

Small jaws mounted on a muscularized
extension of the body wall (jaw-like
pincers). – keep outer surface clean (e.g. from
settling larvae). – may be poisonous (defensive). – respond to touch, food and other stimuli.

Question 9

Explain the Ambulacral Vascular system in echinoderms

Answer 9

System opens to outside via
madreporite, a porous “stone pore” leading to
a stone canal leading to
a ring ‘circumoral’ canal, with
5 radial canals, each with
paired side branches, each with
a tube foot ‘podium’, each with
an ampulla

Question 10

Function of Components of the WVS - Madreporite

Answer 10

filters sea water into WVS

Question 11

Function of Components of the WVS -Ring canal

Answer 11

surrounds oesophagus

Question 12

Function of Components of the WVS - Radial Canals

Answer 12

radiate from ring & bear tube feet

Question 13

Function of Components of the WVS - Ampullae & Tube feet

Answer 13

locomotion, respiration etc

Tube feet might be sticky (mucous) or bear a sucker.

Ampulla store water to effect movement or extension of tubefeet

Question 14

Function of Components of the WVS - Pollian Vessicles

Answer 14

excess water

Question 15

Function of Components of the WVS - Tiedmann’s Bodies

Answer 15

Produce coelomic amebocytes corpuscles to destroy waste (bacteria )

Question 16

Characteristics of Echinoderm Nervous System

Answer 16

No brain; no cephalization
Peripheral diffused system (nerve net).
No elaborate sense organs.
Statocysts for equilibrium
Chemoreceptors.