Labeo Umbratus Lab Report

The internal and external anatomy of Labeo umbratus
Hannah Janse van Vuuren

Abstract

The anatomy of an Labeo umbratus specimen, found in the Krugersdrif dam, was studied. Annotations of the positions of the internal organs as well as the external morphological characteristics were made. Upon further analysis, several characteristics were identified that would have eased life in aquatic environments. Some of these characteristics include sensory receptors located on the head as well as on the lateral view of the body, the shape of the fish, specialised, paired appendages, respiratory structures, as well as structures aiding the fish in buoyancy. The way in which the internal organs and the external appendages were arranged in

The contained structures in the mouth are: the jaws, teeth and gums. Other structures as part of the external anatomy includes, fin, the lateral line, anus, eye, operculum covering the gills.

Some of the essential materials used during the dissection, in accordance with Heit & Klusek (1982), was a lab coat as well as surgical gloves that had to be worn, in order to prevent staining your clothes and lessening the mess and smell of dissected fish. Other materials included, clean, stainless steel dissection tools and a dissecting board.

The first step of the dissecting process was to place the fish on the dissecting board to prevent damage to the counter top. The first incision was made using scissors between the anal and pectoral fins. Two parallel vertical incisions were then made, followed by a horizontal cut on the dorsal side of the fish in order to remove the fillet. When making the incisions, one must be careful not to cut to deep and damage the internal organs. After the fillet has been removed, the ribs can be observed. The internal anatomy is presented by the drawing in figure 2.
Figure

Through the way of scissors a cut is made from the base of the operculum to the eye, as close as possible. The operculum can be removed and the gills are exposed. Most fishes have four gills on the lateral sides near the head. Any mucus, present on the gills, have to be removed to get a clear view of the arches. The gills are layered and a probe is used to separate the gill arches. The gills are removed from the head by carefully cutting the cartilage attachments, with a scalpel. The fan-like gill rakers can then be observed. The head is removed, to better observe the transverse part of the body and provides a better view of the kidney located in the head. Incisions are made behind the opercula to form a flap. Three thin slices (0.3 cm) of muscle and cartilage are consecutively removed from the head until three pea-shaped structures are revealed in a cavity. The brain is removed from the cavity by gently probing and scraping it out with a scalpel.

Finally, the eye is removed from the socket by means of protruding a finger through the gills and loosening the muscles around the eye and it is pushed out from the socket. From the outside the eye is gently pulled away from the head to detach it completely from the