Osteichthyes Flashcards
From cartilage to bone
Insight from embryo development
The transition of cartilage to bone is the basis by which all long bones form. This transition is tightly regulated to ensure both permissive foetal development through endochondral ossification
From cartilage to bone
Mineralization
The skeleton is enforced with calcium-phosphate (inorganic part) together with the collagen (organic part)
This makes the skeleton stronger and more resilience
Basic cartilage microanatomy
Chondrocytes
*ECM with collagen fibres &rubbery glycoproteins
*No blood vessels
*Cells do not divide often in adults
Function:Support outer ears, nose,airways
Basic bone microanatomy
*Bone cells’
*Osteoblasts
*Secrete components of ECM
*Osteocytes
*Mature osteoblasts
*Surrounded by ECM
*Most abundant
*Osteoclasts
*Break down ECM with acids, enzymes
*Mineralized ECM
*mainly collagen, calcium & phosphorous salt
Advantages of having a bony skeleton
- Defense Stronger bones don’t break that easily, protecting the softer organs of the body
- Insulation of electric signals less vulnerable to sharks (Lorenzini)
- Phosphorus storage Essential for membranes, and nucleic acids, and is generally rare in marine environments
- Fat storage in the yellow bone marrow
- Improved feeding mechanism (stronger jaws)
- Blood cells’ production From the red bone marrow
Ray-finned fish
Basic Anatomy
4 or 5 pairs of gills in a common chamber, covered by operculum
Developed nervous system and sensory organs (lateral line, eyes etc.)Gallbladder gas filled sac
Swim bladder
It is filled with air and covers up to 7% of the body’s volume
Passive buoyancy so the fins are freed from this task
Derived from a pharyngeal outgrowth that at some point will give birth to lungs
Secondarily lost in some forms
Homocercal tail
More speed
Caudal fin free of its buoyancy role
Heterocercal in some primitive bony fish
