Deuterostindx

CLADE DEUTEROSTOME
Phylum Echinodermata
(Note the diversity of this phylum)

CLADE DEUTEROSTOME

Phylum Echinodermata

(Note the diversity of this phylum)

Class Echinoidea

(sand dollars, sea biscuits, and sea urchins)

Sand Dollar

Sea Biscuits

An aboral view of two live sea urchins.

Notice the tube feet interspersed among the urchin's spines moving a portion of a dead sea star toward the mouth opening on the under surface of the animal.

These images shows the test of a sea urchin after having lost its spines.

Class Ophiuroidea

(brittle stars)

Aboral view of a brittle star

Oral side of the brittle star

Class Asteroidea

(sea stars, sometimes referred to as star fish)

Our study of this phylum will focus on sea stars.

External Anatomy of the sea star

Preserved sea star, aboral view

Preserved sea star, madreporite indicated by arrow.

Oral view showing mouth opening & tube feet retracted

Sea stars keep themselves clean of algae and other encrusting organisms by the use of pincerlike structures called pedicellariae. The image on the right is a magnified view of a pedicellaria from a small sea star stained with a dye for contratst. It measures appoximately 300 um in length. Why do you think it is important to keep the surface of this animal clean?



Oral surface showing ambulacral grooves of a live sea star.	Close up of ambulacral grooves showing suction-cup like tube feet.

Oral surface showing ambulacral grooves of a live sea star.

Close up of ambulacral grooves showing suction-cup like tube feet.

Internal Anatomy of the Sea Star

The upper body wall of this sea star has been removed. Numbers 1, 3, and 4 show the pyloric caecae which are digestive glands located in each arm of the sea star. Arm numbers 2 and 5 have had the pyloric caecae removed to reveal the ambulacral ridge. (aboral view)

The arrow indicates the stone canal attached to the external madreporite. Note the membraneous material over the ring canal is a portion of the lower stomach.

After removing the stomach, intestinal caeca, and pyloric caeca, the area marked indicates the location of the ring canal which connects the radial canals of the sea star.

What are the important features of the water vascular system in the sea star and how do they function?


This cross section of a sea star arm shows the external spines (1), the pyloric caecum (2), and retracted tube feet(3).	A prepared slide of this same region also shows external spines(1), the pyloric caecum(2), and tube feet extended(3).

This cross section of a sea star arm shows the external spines (1), the pyloric caecum (2), and retracted tube feet(3).

A prepared slide of this same region also shows external spines(1), the pyloric caecum(2), and tube feet extended(3).

Class Holothuroidea

(sea cucumbers)

Image of full size sea cucumber coming soon!

This image of a live sea cucumber was captured in our school's fish tank. Note the spiny covering and feeding tenacles around the mouth.

Phylum Chordata

Subphylum Urochordata

(commonly called sea squirts or tunicates)

A tadpole larva of a tunicate with a post anal tail and notochord.

Adult tunicate (Molgula) (preserved)

Adult tunicate with tunic removed.

A close-up this animal with the tunic removed shows the pharyngeal basket (3), the incurent siphon (1), the excurrent siphon(2) and the digestive/reproductive organs (4)

Phylum Chordata

Subphylum Cephalochordata

(Commonly called lancelets)

An adult lancelet, stained and mounted on a microscope slide for study. The actual size of this animal is approximately 3 cm.

Viewing the anterior end of the animal note the oral cirri(1) and the striation of the pharyngeal basket(2) used in feeding.

Coming soon the posterior end of a lancelet!


As you look at this cross section of a lancelet, note the dorsal fin(1), the hollow dorsal nerve cord(2), and the notochord(3). Note: The nerve cord and notochord are not the same structure.

As you look at this cross section of a lancelet, note the dorsal fin(1), the hollow dorsal nerve cord(2), and the notochord(3). Note: The nerve cord and notochord are not the same structure.

Phylum Chordata
Subphylum Vertebrata
Class Osteichthyes (bony fishes)
External anatomy	Name the body regions and structures visible in this trout.

Phylum Chordata

Subphylum Vertebrata

Class Osteichthyes

(bony fishes)

External anatomy

Name the body regions and structures visible in this trout.

Internal anatomy

The main structures to identify are labeled here. They are the swim bladder(1), kidney(2), intestine(3), spleen(4), pyloric caecae(5), stomach(6), liver(7), heart(8), and the gills(9). Understand the function of these structures.

Close-up view of the gills attached to the gill bar.

Close-up view of the heart. When removed the heart is triagular in shape.

Credits:
Photos and text by Linda M. Westagte
last update March 2008

Credits:

Photos and text by Linda M. Westagte

last update March 2008

Review questions for external anatomy:
How would you describe the symmetry of this animal?
Can you determine a posterior or anterior end?
What is the function of the madreporite?
What is the function of pedicellaria?
Where is the mouth located?
Where is the anus located?
What is the function of the tube feet?
What organ system do echinoderms have that no other animal group has?


Class Ophiuroidea (brittle stars)
	Aboral view of a brittle star	Oral side of the brittle star

Phylum Chordata
Subphylum Cephalochordata (Commonly called lancelets)

	An adult lancelet, stained and mounted on a microscope slide for study. The actual size of this animal is approximately 3 cm.

	Viewing the anterior end of the animal note the oral cirri(1) and the striation of the pharyngeal basket(2) used in feeding.
	Coming soon the posterior end of a lancelet!