Sea Urchin Genome Reveals Striking Similarities to Humans

Sea urchins and humans have a remarkable amount in common?genetically speaking.

Scientists already knew that the creatures, which resemble underwater hedgehogs, are one of only a few invertebrates (animals without backbones) on the human branch of the evolutionary tree.

But a new sequence of the California purple urchin's genome reveals that the marine creatures and humans bear a striking number of similarities ... The scientists identified more than 23,000 genes in the 814 million base pairs, or "letters," of DNA code taken from the sea urchin.

The sea urchin represents the first sequenced genome from the echinoderms, which are the closest known relatives of the chordates, the group that includes vertebrates, animals with spinal columns. ... The genome includes analogs to many essential human genes that were previously thought to be exclusive to vertebrates.

But missing among the sea urchin genes are some genes found in flies and worms. This, scientists say, shows that sea urchins are closer kin to humans than beetles, flies, crabs, and clams.

"Humans and sea urchins have a common ancestor," Weinstock said. The eyeless sea urchin also has genes associated with taste, smell, hearing, balance?and surprisingly, even vision. - natgeo