19_Actinopterygii_2020.pptx - CLASS ACTINOPTERYGII and...

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1 CLASS ACTINOPTERYGII and Sarcopterygii Ray-finned Bony Fishes BIOL1309 Evolutionary Diversity Photo by C. Yau: Sunfish ( Mola mola ) in Lisbon Aquarium
2 PHYLUM CHORDATA Phylum CHORDATA Subphylum VERTEBRATA Infraphylum GNATHOSTOMATA (jawed vertebrates) OSTEICHTHYES (bony fishes) Class ACTINOPTERYGII (ray-finned fishes) Sarcoptergyii Actinoptergyii Acanthodii Chondrichthyes Placodermi Osteichthyes Teleostomi Gnathostomata ( = Extinct)
Red is bone; blue is cartilage Chondrichyes Bony fishes
4 OSTEICHTHYES Osteichthyes (“ os-tee-ik-thees” meaning ‘bony fishes ) are the bony fishes. Evolved approx. 400 million years ago (mya), perhaps earlier even than the Chondrichthyes Osteichthyes 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”
6 Osteichthyes: General Charcteristics Endoskeleton 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; intermediate form still with some cartilage
8 Skeleton of a Bony Fish Bony endoskeleton of an Osteichthyes
9 Osteichthyes The distinguishing character that separates the Osteichthyes concerns the structure of the paired fins . I . Class ACTINOPTERYGII ray-finned fishes : fins are formed by the dermal fin rays; the endoskeleton and muscles controlling the fins remain within the body. II . Class SARCOPTERYGII lobe-finned fishes : fins are fleshy; skeleton supporting the fin and its associated musculature project outside the body, forming a fleshy base. Actinopterygii - rockfish Sarcopterygii - lungfish
10 I. CLASS ACTINOPTERYGII The Actinopterygi i (“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.

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