Understanding the Water Vascular System in Animals

The question asks to identify which animal among the given options possesses a well-developed water vascular system. This system is a unique characteristic of a specific group of marine animals.

What is a Water Vascular System?

A water vascular system is a hydraulic system used by echinoderms (like starfish, sea urchins, and sea cucumbers) for locomotion, food collection, and respiration. It consists of a network of canals filled with seawater, branching throughout the body. Key components include:

• Madreporite: A sieve-like plate that allows water to enter the system.
• Stone Canal: Connects the madreporite to the ring canal.
• Ring Canal: Encircles the mouth.
• Radial Canals: Extend from the ring canal into each arm.
• Tube Feet: Small, flexible, hollow appendages extending from the radial canals, used for movement and capturing prey.

Analysis of the Given Options

1. Starfish

Starfish belong to the phylum Echinodermata. They are known for their distinct water vascular system, which powers their tube feet. This system is crucial for their movement across surfaces, anchoring themselves, manipulating food, and even respiration. Therefore, the starfish possesses a well-developed water vascular system.

2. Sponge

Sponges (phylum Porifera) are simple multicellular animals. They have a system of canals and chambers lined with flagellated cells (choanocytes) that create water currents. This system helps in filter-feeding and gas exchange, but it is not considered a water vascular system in the way it exists in echinoderms. It lacks the complexity and specific components like tube feet.

3. Hydra

Hydra belongs to the phylum Cnidaria. It has a simple body plan with a central gastrovascular cavity that serves for both digestion and circulation. It does not possess specialized systems like a water vascular system for locomotion or feeding.

4. Jellyfish

Jellyfish, also belonging to the phylum Cnidaria, move primarily through muscle contractions of their bell and buoyancy. They have a gastrovascular cavity for digestion and nutrient distribution. They lack the intricate hydraulic network characteristic of a water vascular system.

Conclusion

Based on the analysis, the starfish is the animal among the choices that characteristically possesses a well-developed water vascular system, enabling functions like locomotion via tube feet.