What are the basic characteristics of the class Cephalaspidomorphi?
Cephalaspidomorphi were, like most contemporary fishes, very well armoured. The head shield was particularly well developed, protecting the head, gills and the anterior section of the viscera. The body was in most forms well armoured as well.
Does Cephalaspidomorphi have jaws?
Lamprey are by far some of the most primitive fish, along with hagfish. They are called cyclostomes, meaning ’round mouths’ which refers to their lack of jaws.
Are hagfish Cephalaspidomorphi?
Hagfish (Mixini) and lampreys (Cephalaspidomorphi) do not have a jaw, which easily differentiates them from other vertebrates (Fig. 1.3A). Fish that migrate between freshwater and salt water to spawn are called Diadromous.
Do Cephalaspidomorphi have bones?
PHYSICAL CHARACTERISTICS Lampreys (LAM-prees) are scaleless, eel-like fishes that have skeletons of cartilage (KAR-teh-lej) instead of bone.
What is the most primitive fish?
The first group is the Superclass Agnatha. This group is the most primitive of the three groups of fish. The fish belonging to this group have no jaws. Their mouths are like holes in their heads that lack movable parts.
How are cephalaspidomorphs related to the lampreys?
Jump to navigation Jump to search. Cephalaspidomorphs are a group of jawless fishes named for Cephalaspis of the osteostracans. Most biologists regard this taxon as extinct, but the name is sometimes used in the classification of lampreys, because lampreys were once thought to be related to cephalaspids.
What kind of body does a Cephalaspidomorphi have?
Cephalaspidomorphi were, like most contemporary fishes, very well armoured. The head shield was particularly well developed, protecting the head, gills and the anterior section of the viscera. The body was in most forms well armoured as well.
How are the osteostracans related to the Cephalaspidomorphi?
In the 1920s, the biologists Johan Kiær and Erik Stensiö first recognized the Cephalaspidomorphi as including the osteostracans, anaspids, and lampreys, because all three groups share a single dorsal “nostril”, now known as a nasohypophysial opening. Since then, opinions on the relations among jawless vertebrates have varied.
What kind of body does Cephalaspis lyellii have?
Biology and Morphology. Reconstruction of Cephalaspis lyellii. Cephalaspidomorphi were, like most contemporary fishes, very well armoured. The head shield was particularly well developed, protecting the head, gills and the anterior section of the viscera. The body was in most forms well armoured as well.