Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Biology 455 – Entomology Lab Insect Anatomy During this lab, you will explore the external and internal anatomy of a cricket. This lab is intended to familiarize you with the general morphology of insects, and to introduce you to the vocabulary of insect “parts”. You will need to know and use this stuff as you identify and study various specimens throughout the course. You are expected to know the underlined terms, and to be able to identify the corresponding body parts on an insect specimen. The lab is self-paced. Work through the handout, making sure that you can find and identify each of the body parts listed, and that you can answer any questions. Pertinent diagrams are included to help you, but you should also make your own sketches and notes. I. External Anatomy • Examine your cricket and identify the 3 main body regions: head, thorax, and abdomen. A. Head • An insects head is connected to the thorax by the flexible cervix (neck). • Locate the cervical sclerites on the cervix. (A sclerite is a hardened plate on an insect’s exoskeleton) Head structures: • Locate the epicranial suture that divides the head into two parietal areas. The frons is bound by the antennae. The gena is the “cheek” region below the eye. It is separated from the frons by the genal suture. The clypeus lies below the frons. The labrum is attached to the lower border of the clypeus and forms the anterior cover of the buccal cavity. The sclerites at the posterior end of the head form the occiput. • On the antennae, distinguish the scape, pedicel, and flagellum. • The compound eye is composed of ommatidial facets. • Locate the median and lateral ocelli. Mouthparts: • Detach and examine the series of mouthparts, working from anterior to posterior. Consider the structure and function of each part carefully. • Mandibles: detach and examine the mandibles. Are they symmetric? • Maxillae: Locate cardo, stipes, lacinia, galea, and maxillary palps. • Labium: This forms the posterior closure of the buccal cavity. Locate the postmentum, prementum, ligula (=glossae and paraglossae), and labial palps. • Hypopharynx: this is the “tongue” on the anterior surface of the labium. B. Thorax • Distinguish the prothorax, mesothorax, and metathorax. • Locate the dorsal nota (tergum). Locate the pleuron and the pleural suture that separates the episternum and epimeron. On the ventral side, locate the sternellum. Locate the thoracic spiracles. Wings: • With what body segments are the wings associated? • What do you think are some of the functional distinctions of front and hind wings? • Locate the axillary sclerites. We will examine wing structure and morphology in more detail later. Legs: • The proximal segment of a leg is the coxa. The trochanter articulates with the coxa, and is fixed to the femur. The femur is connected to the tibia, which in turn is connected to a series of segments called the tarsus. At the distal end of the tarsus is the pretarsus. The pretarsus includes a pair of tarsal claws and a pulvillus. • How many tarsal segments does a cricket have? C. Abdomen • There are 11 abdominal segments. How many of them can you distinguish? • The anterior 7 are always distinct. Identify the tergum, sternum, pleuron, and spiracles on each. • The posterior 4 segments are variously modified and carry the genitalia and cerci. Locate the epiproct, paraprocts, cerci, anus, and genital aperture. • Is your cricket male of female? How do you distinguish the sexes? II. Internal anatomy To examine the internal anatomy, you will have to dissect a cricket. Anesthetize a cricket with CO2 or cool it on ice. Place the cricket in a dissecting dish and pin it as demonstrated. Carefully remove the wings. Cover the cricket with saline, and cut it open along the midline, posterior to anterior. • • Locate the silvery, air-filled tracheal tubes and air sacs. Trace them to the spiracles. Locate the fat body. Gonads and accessory glands: • In a female cricket, locate the ovaries and identify the ovarioles. Locate the oviduct and spermatheca. • In a male cricket, locate the testes and seminal vesicles. Locate the mushroom gland, ejaculatory duct, and aedeagus (penis). Gut: • Identify the pharynx, esophagus, crop, and proventriculus of the foregut. Identify the gastric caeca, ventriculus, and pylorus of the midgut. Identify the ileum (colon), rectum, and anus of the hindgut. • Identify the Malpighian tubules. • Open the crop and proventriculus and examine their interior structure. What do you think the crop and proventriculus do? Nervous system: • The insect nervous system is located ventrally along the body axis, and is composed of a series of ganglia. Locate the subesophageal ganglion. CUTICLE, CROSS SECTION HEAD DIGESTIVE SYSTEM MOUTHPARTS LEGS REPRODUCTIVE SYSTEM NERVOUS SYSTEM RESPIRATORY SYSTEM CIRCULATORY SYSTEM