Approximately 95 million years ago, the ancestor of today’s dolphin, the Mesonix, roamed the earth. It was a land animal that went into the water to eat. It had front legs and back legs and was covered with hair. Plenty of the research that has been conducted shows that this is with the Artiodactyl order. It is believed that the ancestors of dolphins that we know today entered the water about 50 million years ago!
Dino ACROCANTHOSAURUS: (ak-ro-KANTH-o-sawr-us) "High-spined Lizard" (Greek akro- = high akantha = spine + sauros = lizard, refering to the spines on its vertebrae) A CARNOSAUR of Early Creataceous North America. This 40 foot (12m) meat-eating relative of ALLOSAURUS walked on two legs. It had a large head with sharp, sawlike TEETH. Projections up to 17 inches (43 cm) long grew on its vertebarae. These SPINES were probably embedded in a thick ridge of muscle.
Zachary Hill March 2, 2014 BIO 121.01 Elephant Shark Summary During the Paleozoic era, about 450 million years ago, a separation occurred in gnathostomes. Gnathostome creatures are vertebrates that have paired fins and a hinged jaw, but separated by weather they are a bony vertebrate, or a cartilaginous. Bony fish are formally known as osteichthyes, they include fish with ossified endoskeletons such as a salmon would have. Cartilaginous fishes on the contrary have cartilage endoskeletons, and are referred to as chondrichthyes. These fish evolved from each other over time, and by analyzing their genomes we can obtain insights on their ancestry.
Heather Capp Dr. Campese Psych 300 October 20, 2012 Electroreception in Sharks Electroreception is an acute sensitivity to bioelectric fields found primarily in aquatic vertebrates as either a passive or active skill. Electroreceptive animals make use of weak electric currents chiefly to locate objects around them, particularly prey .This ability can also be used to avoid predation and in geomagnetic navigation. Sharks, like other members of the Elasmobranch family, possess electroreceptors called ampullae of Lorenzini, which are scattered over their heads in distinct clusters. They are an extension of the lateral line, which is a long, hollow sensory organ stretching down sharks’ sides from gill to tail with perforated scale openings, allowing the sharks to sense water pressure, direction, and displacement. Ampullae of Lorenzini are used in passive electroreception, which utilizes the animate and inanimate electric fields generated by the activity of nerves and muscles in other animals in order to detect them.
Plants, animals, protists, and fungi are all organisms inclusive to this domain. The octopus's next level of taxonomic classification is the kingdom animalia. Defining characteristics of the kingdom animalia include being heterotrophic. Heterotrophic organisms do not have any means of producing their own food, and therefore are required to feed off other organisms for sustenance. Animalia are also multicellular organisms, and they can sexually reproduce.
We know this thanks to preservation of soft tissues found on some trilobite fossils. The same fossils are also found in freshwater environments, suggesting that some freshwater trilobites existed among saltwater trilobites. Up to the late Devonian Period they were very diverse, and likely there were trilobites that specialized in most every type of marine food source. Some definitely burrowed in the mud of the sea bed, likely eating anything they found there. Others would have been active predators and hunted other trilobites, worms, etc.
Its mouth is at the front of the head and not underside like most sharks. On this massive giant, are a wide flat head, a rounded snout, small eyes, five gill slits, two dorsal fins, and two pectoral fins (The Whale Shark Bibliography – Tethys Marine). The spiracle is also located just behind the shark s eye. And another distinguishing feature is that its tail has a top fin much larger than the lower fin. Another unique characteristic is that the whale shark has a distinctive light yellow marking on its body.
“A pencil is one of the best eyes” says Professor Agassiz. However, after hearing the results of his observation, he insists that he looks deeper at the fish. Professor Agassiz returns a couple of times and asks him what he sees. Each time he leaves, dissatisfied at Scudder’s answer. He returns one last time and asks Scudder of his discoveries.
Having learned of the existence of immortal life, you would expect that scientists would start to dedicate enormous amounts of money and resources into learning about how the jellyfish is able to resist death. Perhaps pharmaceutical firms and doctors all over the world would try to gain knowledge of this unending life and try to use it to aid modern medicine. But not much has happened. In the last twenty-five years some progress has been made though. We have learned that the rejuvenation of the Turritopsis dohnii is caused by either environmental stress or physical harm.