Chapter 27 - Anatomy, Physiology, and Behavior

Abstract

The anatomical, physiological, and behavioral characteristics of the laboratory golden Syrian hamster (Mesocricetus auratus) are summarized in this chapter. The anatomical characteristics are the external features, musculoskeletal system, and the digestive system. An adult Syrian hamster is approximately 14–19 cm in length and weighs approximately 114–140 gm. Hamsters have thick compact bodies with short legs, a short tail, large cheek pouches, and excess loose skin. The free margins of the lips form a three-cornered flap, which seals the mouth opening when closed and aids in filling the cheek pouches. The hamster stomach is approximately 3.5 cm long and 2.0 cm wide and is divided into two distinct areas: glandular stomach and nonglandular forestomach. Furthermore the chapter explains the circulatory system, pulmonary system, genitourinary system, and the nervous system. The four-chambered heart is located at the level of the third to fifth thoracic ribs. The pulmonary and aortic valves are tricuspid. Both the left and right atrioventricular valves have two major and two minor accessory leaflets. The respiratory system of the hamster consists of the nasal cavity, nasal sinuses, pharynx, larynx, trachea, and lungs. The average total weight of the hamster brain is 1.4 grams. The cerebral hemispheres consist of large frontal, lateral, and occipital lobes. The sulcus paramedius is low and flat, while the caudal uvula is lengthened considerably. Hamsters are nocturnal animals that live singly or as a mother with litter in the wild. The chapter also analyzes the behavioral patterns of hamsters. Hamsters spend a significant amount of their time asleep (41%) and the amount of time spent sleeping increases with age. Both male and female hamsters build nests, with nest-building activity greatly increased during pregnancy and lactation.