Diversity Of Phylum Chordata Essay Example | Topics and Well Written Essays - 2500 words

Diversity Of Phylum phylum Chordata - Essay ExampleIn fish they are modified to form gills and they may disappear as the animal grows especially in just about of the vertebrates. The pharyngeal gill slit is present at some point in life of the animals. Nerve cord It is hollow and dorsoventrally placed to the nonochord and ends in the brain. some other features are muscular tail (post anal tail) and endostyle (a groove like structure in the ventral contend of the pharynx. However the general features exhibited by animals in this phylum are The animals endure a bilaterally symmetrical consistence Their bodies are segmented and therefore have segmented muscles Their coelom is considerably developed They have well developed circulatory system with a ventrally placed heart and are therefore more active than their counterpart invertebrates. Their skeleton is either bony or cartilaginous Their digestive system is realised meaning that their gut runs through the automobile trunk f rom mouth to the anus. The phylum chordate falls under the Kingdom animal kingdom and is further divided into the subphyla Urochordata, Cephalochordata and Vertebrata. However, animals in these subphyla may show different characteristics but the reason for them beingness grouped in the same phylum is because they exhibit similar characters referred to as unifying links such as urochordates larvae have both notochord and nerve cord which vanishes in due date. Cephalochordates have a notochord and nerve cord which put up to adulthood but do not have cranium. In vertebrates, the notochord is replaced with vertebral column at adulthood stage and the nerve cord becomes the spinal cord. Subphylum Urochordata Urochordates also known as Tunicates and exemplified by Ascidia have the following characteristics At adult stage, their body is covered with a suck like structure (Tunica) and has cardinal siphons one through which water enters the body (incurrent siphon) and the other through wh ich water leaves the body (excurrent siphon). They are sift feeders and sessile. Although adults are sessile, their larvae are free swimming and exhibit almost all chordate characteristics. Subphylum Cephalochordata Exemplified by amphioxus and lancelets, cephalochordates have eel like bodies, they are marine, their bodies are segmented. Members of the phylum are soft bodied and therefore, cephalochordates are not fossilized. A notochord extends through their elongated body and mouth is armed with cirri which aids in obtaining food. They have many gill slits and are also dioecious. They are filter feeders (extract food from water taken in though the mouth by help of cilia on their wheel organ. Subphylum vertebrata Vertebrates are the most advanced chordates and apart from having an internal skeleton, they exhibit the following characteristics Their bodies are segmented They have a bilateral symmetrical body Their endoskeleton is either a bony or cartilaginous Pharyngeal gill slits are lost in adults but are present during embryonic stage Their heart is ventrally placed They posses post anal tail They have a closed circulatory system Vertebrata tell apartes Classes captured are Agnatha, Chondrichthyes, Osteichthyes,Amphibia ,Reptila ,aves and Mammalia Class Agnatha Agnathans arise from a group of vertebrates known as Cylclostomes (fishes or group of vertebrates without jaws) which excludes Gnathostomes (group of vertebrat