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Humans move by putting one foot in front of the other. Fish swim by moving their tail fin from side to side. Squids have a whole other way of getting where they want to go.
Imagine blowing up a balloon and then letting it go. Air rushes out the back, and the balloon moves in the opposite direction. A similar thing happens with squids. A squid’s body includes a bag made of muscles that fills with water. To move, the squid contracts its muscles, pushing water out and moving itself in the opposite direction. Very much like a balloon.
The 300 different kinds of squids all have a long, tube-shaped body and a small head. They have 10 arms, two of which are actually tentacles. The tentacles of some squids have four rows of sucker cups shaped like sharp hooks. They’re used to grab and hold prey. A squid’s brain is shaped like a donut. ▶
▲ Squids have huge eyes, the biggest of all animals. A giant squid’s eyes are about 10 inches across, the size of a basketball. Their size allows them to see as clearly as possible in the dark depths of the ocean where they live. The cockeyed squid has eyes that are different sizes!
◀ Squids are masters of disguise. Their arms have thousands of tiny pigment, or color, cells. The cells are attached to muscles that can expand or contract. When a muscle contracts, the pigment in the cell expands. When the pigment cell expands, its color shows and changes the color of the squid’s skin.
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How have squids helped engineers solve problems?
Researchers are working on ways to create artificial skin similar to squids’ skin. They have already created a kind of artificial skin that copies what the color cells in squid skin do. Their goal is to create smart clothing that can blend in with the environment. Or clothing that can stand out from the environment to help people in danger.
Squids have three hearts. Two are near their gills. Their third heart is in the main part of their body. The two gill hearts pump blood to the gills where it takes in oxygen from the water. The blood then flows to the systemic, or third, heart, which pumps oxygen-rich blood to the rest of the body. ▶
Squids squirt a cloud of ink to help them escape from danger or to sneak up on prey.
