head structure and function

axial skeleton

includes skull, vertebrae, ribs

appendicular skeleton

includes fin support structures

skull

encloses brain and sensory organs, includes neurocranium and branchiocranium

neurocranium

made up of chondocranium, dermatocranium, ethmoid region, orbital region, otic region, basicranial region

ethmoid region

contains vomer and nasals, part of the skull that can remain cartilaginous in adults

orbital region

contains structures that support eyes

otic region

contains structures that enclose canals for balance and hearing

basicranial region

contains structures that provide attachment points for muscle and first vertebra, and passageway for spinal cord

branchiocranium

made up of mandibular arch and upper jaw

mandibular arch

dermal bones used for jaw suspension

(pre)maxillae

tooth-bearing part of jaw

palatine arch

in upper jaw, make up roof of mouth

opercular series

in upper jaw, dermal bones that protect the gills and aid in respiration

suspensorium

in upper jaw, attaches lower jaw to skull

hyoid complex

in upper jaw, make up floor of mouth

branchial series

in upper jaw, gill arches, gill rakers, pharyngeal teeth patches

gills

thin epithelial membranes with secondary lamellae for maximizing surface area to extract oxygen from water

countercurrent exchange

blood in capillaries flow opposite to water passing over gills, creates an oxygen diffusion gradient

buccal pumping

changing volume of buccal and opercular chambers to push water over the gills

ram ventliation

hanging mouth open while swimming to push water through gills

jaw protrusion

increasing buccal chamber pressure to open mouth and pull food into gill arches/rakers with rapid inflow of water

pharyngeal jaws

2nd set of jaws, modified gill arches, helps crush and rake prey into esophagus

terminal mouth

forward-facing mouth

superior mouth

upward-facing mouth

inferior mouth

downward-facing mouth