GENERAL HISTOLOGY

Detailed explanation-1: -A sea star has 2 stomachs, the cardiac stomach and the pyloric stomach. It can push the cardiac stomach out of its mouth, in the centre of its underside, to engulf prey or insert it into prey (between 2 shells, for example). The stomach then secretes a powerful digestive enzyme to break down the prey.

Detailed explanation-2: -Echinoderms have a unique system for gas exchange, nutrient circulation, and locomotion called the water vascular system. The system consists of a central ring canal and radial canals extending along each arm. Water circulates through these structures allowing for gas, nutrient, and waste exchange.

Detailed explanation-3: -Ampullae: A pouch or sack-like part of the sea star’s water vascular system that expands and contracts to move water up and down each tube foot. When the sea star wants to create a suction at the end of its tube foot, its ampullae pulls water out of the podia.

Detailed explanation-4: -The pyloric ceca (or digestive glands) and the cardiac stomach produce digestive enzymes in starfishes. Digested material is absorbed through the pyloric ceca for transport to the rest of the body. Each pyloric cecum extends the length of each arm.