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The water vascular system is a hydraulic system used by echinoderms, such as sea stars and sea urchins, for locomotion, food and waste transportation, and respiration. [1] The system is composed of canals connecting numerous tube feet. Echinoderms move by alternately contracting muscles that force water into the tube feet, causing them to ...
Ram feeding and suction feeding are on opposite sides of the feeding spectrum, where extreme ram feeding is when a predator swims over an immobile prey item with open jaws to engulf the prey. Extreme suction feeding is demonstrated by sit-and-wait predators that rely on rapid depression of the jaws to capture prey (e.g., frogfish, Antennariidae).
Besides feeding and defense, sea anemone and coral colonies use cnidocytes to sting one another in order to defend or win space. [21] Despite their effectiveness in prey-predator interactions, there is an evolutionary tradeoff as cnidarian venom systems are known to reduce the cnidarian's reproductive fitness and overall growth.
Krill feeding in a high phytoplankton concentration (slowed by a factor of 12). Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a specialized filtering organ that sieves out and/or traps solids.
Hydra oligactis. This species can reproduce in three ways: sexual reproduction, budding, and indirectly through regeneration. [11] When hydra reproduce sexually, simple testes, ovaries, or both will develop on the bodies of an individual. Sperm released into the environment by the testes enters the egg within the ovary.
Diagram of water vascular system of a starfish, showing the ring canal, the radial canals, ampullae (small bulbs), and tube feet Echinoderms possess a unique water vascular system, a network of fluid-filled canals modified from the coelom (body cavity) that function in gas exchange, feeding, sensory reception and locomotion.
The internal anatomy is visible, including the paired siphons to the right A siphon is an anatomical structure which is part of the body of aquatic molluscs in three classes : Gastropoda , Bivalvia and Cephalopoda (members of these classes include saltwater and freshwater snails , clams , octopus , squid and relatives).
The digestive system usually has the following parts: buccal mass (including the mouth, pharynx, and retractor muscles of the pharynx) and salivary glands with salivary ducts; oesophagus and oesophagal crop; stomach, also known as the gastric pouch; digestive gland, also known as the hepatopancreas; intestine; rectum and anus