The Deuterostomes

What are the characteristics of early development in Deuterostomes

The cleavage during the eight-cell stage is radial and indeterminate. The coelom forms from folds in the archenteron. The anus develops from blastopore.

What are some of the differences between an unfertilized egg and a fertilized egg?

The unfertilized egg has a clear nucleus while the fertilized egg doesn’t show a clear one; the fertilized egg also has a membrane/

What are some characteristics of the Phylum Echinodermata?

• Invertebrate

• Marine

• The adults are radially symmetric

• The larvae are bilaterally symmetric

• They have a dermal (endoskeleton) + w/ calcareous plates called ossicles

• Spiny skinned

• Water vascular system with tube feet

What are some of the functions of the tube feet?

Locomotion, gas exchange (respiration), and food acquisition

Class Crinoidea

Sea Lilies

• Flower-like body

Class Echinoidea

• Sea Urchins

• Sand Dollars: Has a combinations of tube feet and spines on oral side

Class Holothuroidea

Sea cucumber

Class Ophiuroidea

• Brittle Stars

• Sea Stars (Starfish)

What are some characteristics of Sea Stars?

• Come in a variety of colors and sizes

• Can have more than 5 arms

Sea Star Anatomy

What are ossicles?

Ossicles form an endoskeleton inside; they are made of calcium carbonate plates.

Water Vascular System

A tube foot (consists of ampulla and podium) 

• When the ampulla squeezes, water is forced into the podium which expands and contacts the ground.  Then, to disengage the muscles shorten the podium.

What are the two stomachs of sea stars?

The pyloric and cardiac stomach

What are the 4 traits of all Chordatas?

1. They have a notochord

2. Ectodermal tissue forms a spinal cord

3. Have muscles and skeletal elements that provide propulsive forces

4. Have suspension feeding devices in inverts and gas exchange in aquatic verts and jaws + hearing invertebrates

What is the notochord for?

It’s a long flexible rod of mesoderm found in all chordates; In vertebrates is replaced by vertebrae or backbone

What are Chordata’s 3 Subphyla?

• Urochordata (Tunicata) - Invertebrate

• Cephalochordata (Lancelet) - Invertebrate

• Vertebrata - Have skull and vertebral column

Urochordata

• Tunicates

• Filter-feeder: Water enters through incurrent siphon into pharynx → food enters dig. system → water exists through excurrent siphon

• All 4 characteristics found during larval stage

Cephalochordata

• Amphioxus (Sea Lancet)

• Adult stage shows all 4 chordates characteristics

• Burrow in sand and filter feed

• Gas exchange across gills and skin

• Have open circulatory system but no heart

Vertebrata

• Has endoskeleton - Including a vertebral column (backbone)

• Development of jaw can be seen

• Lungs

• Stronger limbs

• Eggs have a membrane

Yellow Perch - Bony Fish

• Has bony endoskeleton made of calcium phosphate

• Maintains buoyancy equal to the surrounding water by using swim bladder

• Their scales are made of calcium carbonate