Red is bone; blue is cartilageChondrichyesBony fishes
4OSTEICHTHYESOsteichthyes(“os-tee-ik-thees” meaning ‘bony fishes’) are the bony fishes.Evolved approx. 400 million years ago (mya), perhaps earlier even than the ChondrichthyesOsteichthyes are paraphyletic with land vertebrates (i.e. the tetrapods)An extremely species-rich and morphologically diverse group of vertebrates
5“Fish” or “Fishes”Technically, there is specific usage on when to use the terms “fish” or “fishes”.Plural, more than one species = “fishes”Plural, one species = “fish”Singular = “fish”
6Osteichthyes: General CharcteristicsEndoskeleton is ossified, i.e. bone material is deposited.Bone is heavier than cartilage, but is stronger and provides more stability.Cartilage forms first in the larvae, but this is gradually replaced by bone.Fish larva (family Engraulidae) – note the vertebral column
Young sturgeon (early Actinopterygii); red is bone, blue is cartilage; intermediateform still with some cartilage
8Skeleton of a Bony FishBony endoskeleton of an Osteichthyes
9OsteichthyesThe distinguishing character that separates the Osteichthyes concerns the structure of the paired fins. I. Class ACTINOPTERYGIIray-finned fishes: fins are formed by the dermal fin rays; the endoskeleton and muscles controlling the fins remain within the body. II. Class SARCOPTERYGIIlobe-finned fishes: fins are fleshy; skeleton supporting the fin and its associated musculature project outside the body, forming a fleshy base. Actinopterygii - rockfishSarcopterygii - lungfish
10I. CLASS ACTINOPTERYGIIThe Actinopterygii(“ack-tin-o-te-rij-ee-aye”) are the ray-finned fishes, so-called because the fins are webs of skin supported by bony spines or soft fin rays.