ralph+barbara


 * A male flour beetle (Tribolium castaneum) can mate and impregnate a female he has never met. No other animal is known to have sex by proxy in this way. Many males often mate with each female. The first male will deposit sperm in the female, then a second will arrive and use its spiny genitalia to scrape out his competitor's sperm, before mating itself. Much of the sperm of the first male is carried unwittingly by the second male on its genitalia. One in eight females are fertilised by proxy. **


 * Mollusks were among the first inhabitants of the Earth. Fossils of mollusks have been found in rocks and date back over 500 million years. Mollusk fossils are usually well preserved because of their hard shell.**


 *  Modern arthropods include insects, spiders, centipedes, shrimp, and crayfish. All arthropods are the descendents of a single common ancestor. Just as you and your biological cousins can trace your ancestry back to a common set of grandparents, all arthropods can trace their ancestry back to a common arthropod ancestor. Any species descended from that ancestor is an arthropod. And any species not descended from that ancestor is not an arthropod. and chitons have eight shells. Some mollusks however, lost their shells completely, like some snails, but also like squid and octopi. The giant squid is the largest at 20 **
 * The echinoderms are a group of animals that includes starfish, urchins, feather stars, and sea cucumbers. They are simple animals, lacking a brain and complex sensing organs. Echinoderms are characterized by their radial symmetry and a central mouth. Although a sea urchin looks round, closer inspection reveals that it is nothing more than a starfish with its legs wrapped inwards to form a sphere. The echinoderms are found in a stunning variety of shapes and colors, and are found decorating coral reefs around the world. Some of these animals are carnivorous, feeding on corals and scavenging the ocean floor. Certain species of starfish actually extend their stomachs into their unwary victims in order to digest them. The feather stars and sea cucumbers are mainly filter feeders, catching what ever they can find floating in the ocean currents. **

The vertebrate class Aves includes the birds, an extremely distinctive and successful clade, with an estimated 9000 species worldwide, including the snowy owl pictured here.