Understanding Insect Anatomy - Lab Report Example

Lab Report 2 Understanding Insect Anatomy Introduction Understanding the insect anatomy is important for various reasons which include classification of the insect and predicting other features that may be associated with that specific insect. Therefore, this experiment was used with the specimen being cockroaches and locusts to be dissected and examine various characteristics that can be used to establish the differences between the two. The experiment was done to help the student learn how to recognize and identify insect’s external features on the insect body. Second, this will help in the correlation of each structure identified with its function and analyze how similar structures in different insects are adapted to perform their functions. These structures include legs, antennae, and mouth parts among others. Figure 1: Major anatomical features of an insect From www.ag.auburn.edu Generally, an insect will have three parts; - the head, the thorax and the abdomen (Orkin, n.d.). The head has various parts which encompass the mouth parts specifically adapted for the different feeding habits seen by the insect, the eyes, compound eyes having many small eyes to have a view from various directions. Three pairs of legs are attached to the thorax. It also has an abdomen with spiracles for gaseous exchange. The basic body of an arthropod which encompass the insects we have in this practical is metameric. This means that there is a larger tagmata which comprises a fused section of ancestral segments and metameres. As indicated earlier, the insect will have three parts i.e. head, thorax and the abdomen. The head is quite small and a dissection will reveal better view of the structures. One will note two compound eyes which are large. The structure of the head will also portray an epicranial suture that incepts at the top of the head and projects just below the eyes. Antennae are also found in pairs on the head with three parts i.e. scape, pedicel, and flagellum. The primitive mouthpart shows the mandible adapted for the insect’s feeding habits. Wings are attached to the thorax. The mode of attachment may differ among different insects. For instance, in cockroaches, there are two pairs of wings with the forewings being attached to the mesothorax, and another pair of weaker hindwings being attached to the metathorax. The legs are also attached to the thorax with each legs having the following parts; - a large coxa, trochanter, large femur, and the tibia, the tarsus, the tarsomeres, claws, and pretarsus. Lastly, the abdomen consists of a sclerotized tergite, sternite, membranous pleura, and the openings to the spiracles. This experiment was done to help the student understand the function of each of the structures as well as their adaptations and differences among insects in their functions. Methods 1. The cockroach (Periplaneta Americana) was pinned from above through the thorax and displaced the front and hind wings on one side of the body. More pins were used to stabilize the cockroach. 2. The student was supposed to draw a diagram of the cockroach labelling the head, antennae, fore and hind wings, the abdomen and the spiracles. 3. The student was supposed to compare the structures with those of a locust (Locusta migratoria) which is also a primitive insect. However, the locust was not to be pinned as the cockroach. 4. The features shared by the two insects only among other insects were supposed to be recorded. 5. Draw a labelled diagram of a leg of the locust labelling the trochanter, femur, tibia. Tarsus, and claws. 6. A record of the common features and the differences between the cockroach and locust legs was made. 7. The head of the cockroach was carefully removed by cutting through the membranous neck region. 8. A labelled diagram of the head was drawn from above. 9. Remove the mandibles, maxillae, labium, and labrum from the cockroach mouth parts and note how they form a box around the mouth. 10. Compare the mouthparts of the cockroach with that provided of a hymenoptera (bee). These differences should be recorded in the laboratory hand book. Results The external anatomy of the cockroach shows the head with the compound eyes, the mouth, and the compound eyes (Houseman, n.d.). The fore and hind wings are attached to the thorax as well as the three pairs of legs. The abdomen has spiracle openings responsible for the process of gaseous exchange. Figure 2: View of the cockroach From Quaddoscience.blogspot.com The locust will have the following structures; - Figure 3: Structures seen on a locust From www.biologyjunction.com Taking note of the significant differences in the two structures. Figure 4: The leg of a locust showing the coxa, trochanter, femur, tibia, tarsus and the claws on the posterior side of the tarsus which is not labelled in the image. From. Animals.howstuffworks.com Figure 5: The cockroach head From Microscopy-uk.org.uk. Figure 6: Cockroach mouth parts www.amentsoc.org Discussion Comparing and contrasting the structures of the two instructions will show a number of similarities and differences. The similarities include; - a. They have three pairs of legs each. b. Their heads have similar basic features which include the compound eyes, the mouth parts and the spiracles. c. Their thorax have two pairs of wings and three pairs of legs. d. Their abdomen have spiracles which are used for gaseous exchange. The differences include; - a. A mature locust is considerably bigger than an average mature cockroach. b. The legs in locusts are longer and stronger which is an adaptation for hopping from one location to the other. Locusts are found outdoors while the cockroaches are found indoors therefore their legs are adapted according to the environment they live in. the locust will need long and energetic legs to hop while the cockroach will need a smaller body size and legs which can move swiftly to hide and run from attack. The cockroach is the largest peridomestic insect (University of California). Much work has been done to examine how the cockroach nervous system controls its movement (Hess, 1958) The cockroach mouth parts The cockroach mouth parts are modified for chewing and biting. This is the same structure of mouth part seen in other insects having the primitive type such as the locusts and beetles. That consists of a single labrum which guides food into the mouth, mandibles which are also called the true jaws for chewing and grinding the food, maxillae which serve as the secondary jaws, and the labium which closes the mouth cavity from behind. On the contrary, the bee’s mouth parts are more advanced in structure and are used for feeding their larvae, collecting nectar and pollen, manipulating wax, and carrying things. Bibliography Amateur Entomologist Society. Insects. Available at. Hess, A. (1958). The Fine Structure and Morphological Organization of the Peripheral Nerve-Fibres and Trunks of the Cockroach (Periplaneta Americana). Quarterly Journal of Microscopial Science, 99(3), pp. 333-340. Houseman, G. J. (n.d.). Insect External Anatomy. pp. 1-21. Biology Junction. Invertebrates. Available at. Microscopy.UK. Retrieved From. Orkin. Cockroach Anatomy. Available at. QUADDo Science. (2012). Important Diagrams from Kingdom Animalia-IX Diversity in Living Organisms. Available at. University of California. (n.d.). The American Cockroach. Available at. Weebly. The Anatomy of Insect Legs. Available at. Read More