The water vascular system of echinoderms . a is analogous to the gastrovascular cavity of flatworms b is bilateral in organization, even though the adult animal is not bilaterally symmetrical c functions as a circulatory system that distributes nutrients to body cells d functions in locomotion and feeding

The water vascular system of echinoderms d functions in locomotion and feeding

Explanation:

The water vascular system of echinoderms is a hydraulic system and is an unusual organ system. Echinoderms have a distinct endoskeleton. The water vascular system is essentially a system of fluid-filled canals. It uses water pressure to mediate movement and helps in feeding. It also asists in respiratory, excretory, and some circulatory functions.

The correct answer to the question is option D

FUNCTIONS IN LOCOMOTION AND FEEDING.

The water vascular system in echinoderms functions in locomotion and feeding,it also plays a vital role in gas exchange.

Explanation: Echinoderms are a type of marine organism with a uniquely shaped body known as spiny skin,they belong to the psyllum of marine invertebrates with a true coelom.echinoderms are exclusively marine organism and their body are are derived from ectoderm, mesoderm and endoderm as well as possess a unique organ system grade of organisation,another unique feature of echinoderms is that bilateral symmetry is shown at their larval form and radial symmetry at their adult form.

Another unique feature of echinoderms is the presence of a water vascular system,this water vascular system is hydraulic in nature,it is made up of several fluid filled canals that channels from the body regions of the echinoderm and then projected externally outside the body of the echinoderm, these externally projected channels are known as tube feet.the water vascular system of the echinoderm helps it to feed,move about and breathe (exchange gases).

Examples of echinoderms are; crinoids,sea urchins,sand dollars,sea cucumbers, starfish and brittle stars.

"menstrual cycle is a complex cycle that consists of several processes. order of occurrence of steps in menstrual cycle are as follows:

1. high progesterone levels maintain the endometrium lining of the uterus.

2. endometrium lining breaks down and low levels of estrogen stimulate the pituitary to release fsh and lh.

3. fsh and lh stimulates the follicles to develop and the oocyte to produce estrogen.

4. rising estrogen levels suppress fsh production and development of other follicles.

5. a spike in lh causes follicle to rupture.

6. a breakdown of corpus luteum causes progesterone level to drop."