Shark Skeletal System Web Sites Read pages 16 – 20 in shark book Shark Virtual lab Shark Dissection Images Read pages 16 – 20 in shark book

Endoskeleton Provides support and protection for the softer body parts Fundamental system on which the body is built Skeletal bones Endochondrial bone Dermal / membrane bones Not cartilage solid bone replaces earlier embryological cartilage our arm and leg bones

Squalus acanthius The Skeletal System Axial Skeleton Vertebrates skull vertebral column rib cage

Axial Skeleton CHONDROCRANIUM Shark skull Divided into: Neurocranium anterior and more dorsal part of skull protects brain and sense organs rostrum nares orbits otic capsules - inner ears

Notochord Along the mid ventral line there is a white strand of calcified cartilage This indicates the position of the notochord

Axial Skeleton SPLANCHNOCRANIUM ventral and posterior to the neurocranium also called visceral cranium skeletal visceral arches form the jaws and supports the gill arches

Visceral Arches Supports the mouth and gills Squalus acnathius has only seven Mandibular Arch modified to form the upper and lower jaws Meckel’s cartilage Forms the lower jaw 1st visceral arch Hyoid Arch 2nd visceral arch provides primary support for the jaws and is attached to them by ligaments supports tongue

Gill Arches The last 5 visceral arches (3-7) Support the Gill Elements “U” shaped, multi-jointed Gill lamellae surfaces upon which gas exchange takes place Gill Rakers prevent food from leaving the mouth and pharnyx through the gill slits

Shark Respiratory

Vertebral Column and Ribs Tail Vertebrae Centrum central portion appears white calcified not bone like provides strength to vertebral column Consists of Notochord passes through the center

Dorsal Arch Neural Arch Spinal chord passes through the vertebral canal Ventral Arch Hemal Arch Contains the Hemal Canal through which passes the caudal artery and vein

Trunk Vertebrae similar to that of tail vertebrae lacks the hemal arches Appendicular Skeleton Refers to the cartilages of the pectoral and pelvic girdles Pectoral Girdle “U” shaped structure encircles the ventral side of the trunk consists of a median ventral Caracoid Bar Pectoral Fins 3 basal fin cartilages which articulate with the girdle

Pelvic Girdle composed of a single transverse rod of cartilage puboischaic bar Pelvic Fins in male sharks there is a highly modified radial cartilage that forms the clasper

Dorsal Fins similar in structure to pectoral and pelvic fins larger basal cartilages are proximal to the vertebral column smaller radial cartilages are more distal Caudal Fins end of the vertebral column turns upward into the dorsal part of the caudal fin termed heterocercal

Shark Systems Labeled