Predators & defenses : Many different types of animals prey on adult sea urchins, including birds, sea otters, fishes, crabs, lobsters, octopuses, and sea stars. Eggs and larvae of sea urchins are eaten by many types of carnivorous zooplankters and by suspension-feeding invertebrates including hydroids, sea anemones, and mussels, just to name a few.
IPv4 (Internet Protocol Version 4) is the fourth revision of the Internet Protocol (IP) used to to identify devices on a network through an addressing system. The Internet Protocol is designed for use in interconnected systems of packet-switched computer communication networks (see RFC:791).
Physically, the Internet uses a portion of the total resources of the currently existing public telecommunication networks. Technically, what distinguishes the Internet is its use of a set of protocols called TCP/IP (for Transmission Control Protocol/Internet Protocol). Two recent adaptations of Internet technology, the intranet and the extranet, also make use of the TCP/IP protocol.