Page 25 - SAAT BIOLOGY PART 1

SAAT BIOLOGY MR.MOHAMED ELGAYAR MRPROF.NET
organic material as it floats by. Since they are sessile.

they are not able to pursue their food.

• An exoskeleton is associated with other phyla such as

Arthropoda.

• (No – chordates have a coelom. All chordates have

some kind of segmentation. Invertebrate chordates

have a notochord.)

• An exchange of oxygen and waste excretion can take

place through the thin walls of the tube feet. The

pumping action of the associated water vascular

system can aid the circulation of oxygen and food

materials in some echinoderms.

• The sea cucumbers do not have their tube feet located

on flexible arms.

• Starfish have very prominent arms.

• Brittle stars have very long thin arms.

• Crinoids have arms at the ends of their stalks.

MRPROF.NET MR.MOHAMED ELGAYAR MRPROF.NET@GMAIL.COM 24