Laboratory Exercise II                       

THE DOGFISH SHARK (Squalus acanthias)                                                                                                         

External anatomy:

Specimen: identify all boldfaced structures

Know function: *claspers, *ampullae of Lorenzini, *lateral line system, *incurrent aperture (nostril), *excurrent aperture (nostril), *spiracle, *gills slits, *endolymphatic ducts, *urogenital papilla (male and female), *abdominal pores

Integument:

Slides: identify all boldfaced structures

Know function: *stratum germinativum, *melanophores, *pulp cavity

Skeletal system:

Axial division:

Chondrocranium: rostrum, *nasal capsules, *eye orbits, preorbital process, postorbital process, supraorbital crest, *otic capsules, precerebral cavity, precerebral fenestrae, rostral fenestrae, rostral keel, *epiphyseal foramen, *endolymphatic fossa, *endolymphatic foramina, *foramen magnum, *occipital condyles, external nares, basitrabecular process, basal plate, *optic foramen

        Splanchnocranium:

*branchial arches, pharyngobranchial, epibranchial, ceratobranchial, hypobranchial, basibranchial, *gill rays, *gill rakers

        First arch (mandibular): *palatoquadrate, *Meckel’s cartilage, orbital process

Second arch (hyoid): *hyomandibular cartilages, ceratohyals, basihyal cartilages

Vertebral column (prepared yourself):

Caudal: biconcave centrum, notochord, neural arch, *vertebral canal, neural spine, dorsal intercalary plates, hemal arch, hemal spine, *hemal canal

Trunk: omit

Medial fins: caudal fin, *ceratotrichia, dorsal fins, spines, basal pterygiophore, radial pterygiophores

Appendicular division:

Pectoral girdle and fins: *pectoral girdle, coracoid bar, scapular cartilage, *glenoid surface, suprascapular cartilage, basal pterygiophores (name and identify all three), radial pterygiophores, ceratotrichia

Pelvic girdle and fins: *pelvic girdle, puboischiadic bar, iliac process, *acetabular surface, basal cartilages (name and identify both), radial pterygiophores, ceratotrichia, *clasper

Differentiate among the following anatomical terms: fossa (sp. fossae), crest, process, shelf, foramen (pl. foramina), fenestra (pl. fenestrae)

Muscular system:

Trunk: identify all boldfaced structures

Know function: *myomeres, *myosepta, *linea alba, *horizontal septum, *epaxial muscles, *hypaxial muscles

Pectoral fin: *extensor, *flexor

Pelvic fin: *extensor, *flexor

Dorsal fin: *dorsal fin muscle

Gill arches and their derivatives:

Branchiomeric muscles:

Visceral arch I:

Levators: *levator palatoquadrati

Dorsal constrictors: *spiracularis, *adductor mandibulae

Ventral constrictors: *intermandibularis

Visceral arch II:

Dorsal constrictors: *second dorsal constrictor

Ventral constrictors: *interhyoideus

Visceral arches III- VII:

Levators: *cucullaris

Interarcual muscles: *branchial adductor

Superficial constrictors: *dorsal and ventral constrictors

Hypobranchial muscles: *coracomandibularis, *coracoarcual, *coracohyoid, *coracobranchial

* Know function.  For muscles, a complete “function” would include approximate origin, approximate insertion (specific skeletal elements and/or muscle(s)) and function (including appropriate anatomical terminology).