Final answer:
Jellyfish move by expelling water from their bodies, creating a jet of water that propels them in the opposite direction. Squids have a similar method of propulsion but can control their direction. Both jellyfish and squid use the principles of conservation of momentum to move.
Step-by-step explanation:
Jellyfish move by filling their umbrella sections with water and then pushing the water out of their bodies. This action creates a jet of water, which causes the jellyfish to move in the opposite direction. Their movement is based on the principles of conservation of momentum. Squids also move in a similar way but can control their direction by aiming their nozzle forward or backward. Typical squids can reach speeds of 8 to 12 km/h. Common jellyfish employ an interesting mechanism for movement that is based on the principles of conservation of momentum. These marine invertebrates move by filling their umbrella-shaped bell with water and then rapidly expelling it, causing the jellyfish to propel in the opposite direction.
This action is akin to a jet of water pushing the jellyfish forward, demonstrating a basic form of jet propulsion. Jellyfish movement is generally not directed, as opposed to squids, which can control their movement by adjusting the direction of their nozzle. Other marine invertebrates might employ different modes of movement or may even drift along with ocean currents, lacking the same kind of locomotive ability that jellyfish possess. For example, some invertebrates, like certain species of sea cucumbers and sea stars, move by using their tube feet or attaching themselves to other objects or animals to travel. In contrast, echinoderms such as sea stars possess numerous like tube feet that they use for movement. Some echinoderms use unique methods to travel, such as sea cucumbers that latch onto fish or floating debris.