(Animalia, 2023a; Animalia, 2023b; Diersing, 1984; Jordan, 2005; Li & Ma, 1986; Nowak & Wilson, 1991; Smith et al., 2018; Photograph: CCTV Video News Agency, 2015)

A highly alert animal, the Ili pika exhibits sensitive hearing through its round, short ears. It also has excellent vision and a strong sense of smell (Animalia, 2023a; Li & Ma, 1986). With short hind limbs and forelimbs that are equal in length, the Ili pika stands approximately 8 inches tall and weighs around 6 ounces at maturity (Animalia, 2023b). A coat of thick, soft and silky hair covers its small, stocky body. The pelage of the Ili pika is primarily grey in color with rusty red spots on its forehead and the sides of its neck (Smith et al., 2018). Molting occurs semiannually due to seasonal changes, with females shedding later in the season than males (Jordan, 2005).

With the exception of bare toe pads, long hair covers the feet of the Ili pika. Sharp, curved claws enable it to climb rocks and cliffs in its talus habitat (Animalia, 2023a). The pika is easily identified by its lack of a visible tail (Li & Ma, 1986). Other anatomical characteristics include 22 vertebrae in the thoracic [middle] and lumbar [lower] regions of its spine, no pubic bone and a flattened skull, which is the bone that protects the brain and supports the structure of the face (Diersing, 1984; Fowler et al., 2013). With 26 teeth in total, the Ili pika has two tiny, peg-like teeth directly behind two enameled, V-shaped and ever-growing front incisors (Nowak & Wilson, 1991).

The radiograph below by Schilling and Hackert (2006) of the pika spine displays the 22 vertebrae present in the thoracic and lumbar regions.

(Schilling & Hackert, 2006)

PHYSIOLOGY

DIGESTIVE SYSTEM

(Fowler et al., 2013; Harkness & Wagner, 1989; Jordan, 2005; Li & Ma, 1986; Smith et al., 2018; Diagram: Adapted from Hinić-Frlog, 2020)

The Ili pika has a monogastric digestive system, meaning its stomach has one chamber (Hinić-Frlog, 2020). As a hindgut fermenter, it relies on an enzymatic process called microbial fermentation to obtain nutrients (Smith et al., 2018). The Ili pika consumes an herbivorous diet of plant vegetation including grasses, twigs, sedges and flowers (Jordan, 2005; Li & Ma, 1986).

Digestion begins with food intake through the mouth and down a long tube that connects the mouth to the stomach called the esophagus (Fowler et al., 2013). The muscles contract to push food down the esophagus toward the stomach in a process known as peristalsis (Fowler et al., 2013; Hinić-Frlog, 2020). Upon activation of bile—a digestive juice produced by the liver—and digestive enzymes produced by the pancreas, food breaks down in the stomach and small intestine (Fowler et al., 2013). Waste continues to travel through the large intestine, cecum and colon until excretion via the anus (Smith et al., 2018).

In the Ili pika, an enlarged small intestine and cecum provide more time and surface area for digestion of plant material and absorption of nutrients (Hinić-Frlog, 2020). While indigestible fiber is eliminated as hard and dry pellets, smaller particles and fluids pass into the cecum (Harkness & Wagner, 1989). Soft cecal contents called cecotropes are passed and then re-ingested as a source of vitamin B and vital nutrients (Jordan, 2005).

RESPIRATORY SYSTEM

(Fowler et al., 2013; Harkness & Wagner, 1989; Li & Ma, 1986; Smith et al., 2018; Diagram: Adapted from Science State Board, n.d.)

With respiratory physiology similar to humans, the breathing process of the Ili pika involves the inhalation of oxygen and exhalation of carbon dioxide (Harkness & Wagner, 1989; Science State Board, n.d.). The pika has adapted over time to respiration in high altitudes where there is decreased air pressure with less oxygen available for breathing (Li & Ma, 1986; National Geographic Society, 2022).

Through the external nares, air enters the nasal cavity of the Ili pika, which is the opening of the respiratory system to the outside environment (Fowler et al., 2013; Smith et al., 2018). After warming and humidification in the nasal cavity, air travels through the pharynx and larynx—the throat and voice box, respectively—and is transported from the throat into the lungs through a cartilaginous tube called the trachea (Fowler et al., 2013).

Next, the trachea splits into two branches called bronchi that enter the lungs. Smaller terminal branches called bronchioles spread through the lungs and ultimately lead to alveoli, which are the thin-walled air sacs where gas exchange occurs (Fowler et al., 2013; Science State Board, n.d.). Direct contact between the alveoli and capillaries of the circulatory system ensures the diffusion of oxygen into the blood (Fowler et al., 2013). After oxygen moves into the lungs and bloodstream of the Ili pika upon inhalation, it is carried through the body and exchanged for a waste gas called carbon dioxide; then, it is transported by the bloodstream back to the lungs where it is removed from the blood and exhaled (American Lung Association, 2022).

ENDOCRINE SYSTEM

(Fowler et al., 2013; Harkness & Wagner, 1989; Smith et al., 2018; Diagram: Adapted from Notes on Zoology, n.d.)

Comprised of cells, tissues and organs that release hormones, the endocrine system is vital in maintaining homeostasis within the body of the Ili pika (Fowler et al., 2013; Smith et al., 2018). Hormones, or chemicals that act as a mechanism of communication between cells, are released by endocrine glands into the surrounding interstitial fluid and diffused into the blood (Fowler et al., 2013). 

Inconsistent hormone levels in the Ili pika can be harmful to its health (Harkness & Wagner, 1989). For instance, according to Wilkening et al. (2013), glucocorticoid hormones secreted from the adrenal gland, including cortisol or corticosterone, are released in response to short-term stressors. However, chronic stress causes a continued release of these hormones, potentially leading to negative effects such as nerve cell death, high blood sugar, muscle and bone atrophy, high blood pressure, immunosuppression and reduced reproduction (Wilkening et al., 2013).

The location and secretions of endocrine glands in the body are virtually the same in every vertebrate species (Notes on Zoology, n.d.). A variety of important endocrine glands in the body of the Ili pika and their associated functions are as follows:

• Pituitary gland: Composed of an anterior and posterior region, the pituitary gland is a small nut-like gland positioned at the base of the brain and attached to the hypothalamus (Fowler et al., 2013). Hormones secreted by this gland regulate functions of other glands and play a significant role in chemical coordination of the body (Notes on Zoology, n.d.).

• Thyroid gland: The largest of the endocrine glands, the thyroid gland is located in the neck and produces hormones triiodothyronine and thyroxine. These hormones, also referred to as T3 and T4, stimulate metabolic activity, regulate weight and increase energy use (Fowler et al., 2013).

• Parathyroid glands: Found on the surface of the thyroid, the parathyroid glands produce hormones parathormone and calcitonin (Fowler et al., 2013). Parathyroid hormones are responsible for regulating the amount of calcium and phosphorus in the blood (Notes on Zoology, n.d.).

• Adrenal glands: Located on top of each kidney, the adrenal glands consist of outer cortex and inner medulla that secrete different hormones (Fowler et al., 2013). The cortex releases hormones active in carbohydrate and protein metabolism and electrolyte balance. The medulla produces adrenaline which is responsible for controlling involuntary muscles and blood pressure (Notes on Zoology, n.d.).

• Pancreas: An elongated organ found between the stomach and small intestine, the pancreas contains both exocrine cells that excrete digestive enzymes and endocrine cells that secrete hormones, including insulin and glucagon to regulate blood glucose levels (Fowler et al., 2013).

REPRODUCTION