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.
Jawless Fish (Agnatha). The first vertebrates were the jawless fish. These fish-like animals had hard bony plates that covered their bodies and as their name implies, they did not have jaws. Additionally, these early fish did not have paired fins.y Laura Klappenbach. Vertebrates are a well-known group of animals that includes mammals, birds, reptiles, amphibians, and fish. The defining characteristic of vertebrates is their backbone, an anatomical feature that first appeared in the fossil record about 500 million years ago, during the Ordovician period.