Life History
At first glance, sea urchins often appear sessile, i.e. incapable of moving. Sometimes, the most visible life sign is the spines, which attach to ball-and-socket joints and can point in any direction. In most urchins, touch elicits a prompt reaction from the spines, which converge toward the touch point. Sea urchins have no visible eyes, legs, or means of propulsion, but can move freely over hard surfaces using adhesive tube feet, working in conjunction with the spines.
Read more about this topic: Sea Urchin
Famous quotes containing the words life and/or history:
“Thus was my first year’s life in the woods completed; and the second year was similar to it. I finally left Walden September 6th, 1847.”
—Henry David Thoreau (1817–1862)
“These anyway might think it was important
That human history should not be shortened.”
—Robert Frost (1874–1963)