Lab4Osteichthyes - The Vertebrates Structure Function and...

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1 The Vertebrates: Structure, Function and Evolution (BIOEE 2740) Lab 4 – Osteichthyes, the bony fishes. Goals for this lab: 1. Learn about the diversity and phylogenetic relationships among major groups in the Osteichthyes , the bony fishes. 2. Explore the skeletal, muscular and internal anatomy of the Osteichthyes through dissection of Perca flavescens , the yellow perch. 3. Compare and contrast aspects of skeletal anatomy and morphology among members of the Osteichthyes to gain an understanding of form-function relationships within the Osteichthyes. Station 1. The Osteichthyes – phylogenetic context and synapomorphies The Osteichthyes , the bony fishes, are divided into two major subgroups, the Sarcopterygii , the lobe-finned fishes, and the Actinopterygii , the ray-finned fishes. The Sarcopterygian fishes gave rise to the tetrapods , our focus for the remaining labs in the semester. As humans, we are tetrapods, and thus we are all bony fishes (Osteichthyes)! This week’s lab will focus on the basal (= early-branching) members of the Sarcopterygians, and the Actinopterygians, the group that contains the vast majority of fish diversity. Major concepts The two major divisions within the Osteichthyes are the Sarcopterygii, the lobe-finned fishes, and the Actinopterygii, the ray-finned fishes. With about an estimated 30,000 extant species, actinopteryigian fishes are extraordinarily diverse! Tetrapods are nested within the sarcopterygians, meaning that sarcopterygian fishes gave rise to tetrapods. Tetrapods are members of the Osteichthyes – we are all fish!
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Some major morphological synapomorphies of the Osteichthyes are: 1. Lepidotrichia – this is the bony, segmented support structure in the dorsal, anal, pectoral and pelvic fins of the Osteichthyes. 2. Gas bladder – in most fishes, this is a dorsal outpocketing from the gut known commonly as the swim bladder. In some fishes and all tetrapods, it is a ventral outpocketing of the gut known commonly as lungs. 3. Bony operculum – the operculum is the structure covering the gill slits in the Osteichthyes. Station 2. External anatomy Before working at any of the diversity or anatomy stations, remind yourself of the basic external anatomy of fishes. Identify the mouth, dorsal fin(s), pectoral fins, pelvic fins, caudal fin, anal fin, anus, and lateral line using the diagram below. Also watch out for the adipose fin , a small, rounded, fatty fin located just anterior to the caudal peduncle on the dorsal side of some fishes. Identify the bony operculum, a synapomorphy of the Osteichthyes. Right: Dorsal fin structure of a bony fish. Note the segmented lepidotrichia that form the fin rays. Figure from Liem et al 2001.
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Lab4Osteichthyes - The Vertebrates Structure Function and...

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