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).
The Internet Control Message Protocol (ICMP) is one of the main protocols of the Internet Protocol Suite. It is used by network devices, like routers, to send error messages indicating, for example, that a requested service is not available or that a host or router could not be reached.he ICMP header starts after the IPv4 header and is identified by IP protocol number '1'. All ICMP packets have an 8-byte header and variable-sized data section. The first 4 bytes of the header have fixed format, while the last 4 bytes depend on the type/code of that ICMP packet.