agnathans
Agnatha is a superclass of fish that are characterised by their lack of a jaw as opposed to the presence of a jaw found in most modern fish. The surviving two classes are hagfish and lampreys.
Yes, Time Lords always have 12 regenerations. Some previous episodes have been based around the Doctor's nemesis (the Master) wishing to steal the Doctor's remaining regenerations, and when he ran out of regenerations he looked like a skeleton. Also, River Song used up all of her 'remaining regenerations' to bring the Doctor back to life in 'Let's Kill Hitler', which proves that a Time Lord has a finite number (even if she is only part Time Lord). It is also mentioned somewhere else that they have only 12 regenerations - can't remember where, sorry. Is this what you wanted?
not changing in form or character; remaining the same in all cases and at all times.
I have a strong ethic which include being reliable, upfront and honest about things good or bad, remaining engaged with my coworkers so that not only I can be successful but my team as well. So everyday I put my best foot forward so that my intergrity is never questioned.
the air that enters the respiratory tract remaining in the conducting zone pasageways and never reaches the alveoli.
Lampreys differ from hagfishes by having a notochord that is surrounded by a tube of cartilage.
The skeletons of lampreys and hagfishes are made of cartilage rather than bone. This cartilaginous skeleton provides structure and support to their bodies without the need for true bones.
jawless fishes
Yes pigeons have spleens. All vertebrates have spleens except lampreys and hagfishes.
Lampreys and hagfishes are the only jawless vertebrates to survive today. They both have a round mouth and for this reason are often referred to as cyclostomes.
They also do not have pairs of fins like most fish. But the most remarkable thing about these fish is that they do not have jaws! Instead, the mouths of these fishes have structures for scraping, stabbing. Hagfishes and lampreys are the only living kinds of jawless fishes.
lampreys are only hunted by man
Bony fishHag fishLamprey(both of these are known as the jawless fish)Sharks and rays(both of these are known as cartilaginous fish)Lob-finned fishThis is a very simplified classification of something that is very complex. To see the full tree, try WikiSpieces.
There are three general groups. The first group is jawless fish. They only contain lampreys and hagfishes. The second group is cartilaginous fish, which includes sharks, rays, and their relatives. The last group is bony fish, and they contain every other kind of fish- tuna, clownfish, anglerfish, whatever.
by pooing
n. 1. a class of eel-shaped chordates with a cartilaginous skeleton lacking jaws, scales, and pelvic fins. Among these are the lampreys and hagfishes. There are some extinct forms.
Hagfish and lampreys have gills. They are the only living members of a primitive group of fish without jaws. They have round sucker-like mouths.