Each segment has the same sets of organs and, in most polychaetes, has a pair of parapodia that many species use for locomotion. Septa separate the segments of many species, but are poorly defined or absent in others, and Echiura and Sipuncula show no obvious signs of segmentation.ach segment has the same sets of organs and, in most polychaetes, has a pair of parapodia that many species use for locomotion. Septa separate the segments of many species, but are poorly defined or absent in others, and Echiura and Sipuncula show no obvious signs of segmentation.
Chicxulub is most famous for being near the geographic center of the Chicxulub crater, an impact crater discovered by geologists on the YucatÃ¡n Peninsula and extending into the ocean. It was created by the impact some 65 million years ago of the Chicxulub impactor, an asteroid or comet which caused the CretaceousâPaleogene extinction event, which led to the demise of the dinosaurs.
Only a couple of small Mayan ruins can be found in Cancun, but the city is the gateway to the Mayan empire. Major sites of Mayan ruins, like Chichen Itza and Tulum can be visited on day-trips from Cancun. Chichen Itza, a âmust-seeâ attraction for anyone visiting the Yucatan Peninsula, was named one of the New Seven Wonders of the World, in 2007. In stark contrast to Chichen Itza, which is located deep in the jungle, the ruins of Tulum are on the coast, with panoramic views of the Caribbean Sea.