Different Symptoms for Different Causes of Pain. Orchialgia caused by infection is severe and even in cutting pain accompanied by fever with chilliness, reddened and swollen scrotum, and apparent tenderness. Most bacterial orchitis is caused by adjacent epididymal inflammation, so it is also called epididymo-orchitis.
From Wikipedia, the free encyclopedia. Agnatha (Greek, no jaws) is a superclass of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct (conodonts and ostracoderms) species. The group excludes all vertebrates with jaws, known as gnathostomes.he Agnatha are ectothermic or cold blooded, with a cartilaginous skeleton, and the heart contains 2 chambers.
By the end of the Ordovician Period, primitive jawless fish called Ostracoderms appeared. These primitive fish were covered with bony plates and were among the first vertebrates on the earth. The following image shows how the earth looked approximately 450 Million Years ago, during the Late Ordovician Period.y the end of the Ordovician Period, primitive jawless fish called Ostracoderms appeared. These primitive fish were covered with bony plates and were among the first vertebrates on the earth. The following image shows how the earth looked approximately 450 Million Years ago, during the Late Ordovician Period.