Location/population- They are found in temperate and subarctic latitudes of north Atlantic and north pacific oceans. Some are found in the black and Mediterranean sea. There are 119 different species, and most are abundant type of shark. They are very easy to catch.
Form and Function- They have a short snout, poisonous spine for protection, and a clasper fin(males only).
Shape and Size: Their color is either grey or brown which fades to a white belly with several white spots on sides. They size from 3-4 ft. long. An average length of a spiny dogfish is 28-39 in. Adult Males range from 24-35 in. Adult females range from 30-42in. They weight-7-10 pounds.
Smell- They have a keen sense of smell. They can smell one drop of blood in a million drops of water. They have paired nostrils on the underside of its snout where water continually flows through the nostrils. Unlike humans, shark nostrils have nothing to do with breathing, they are not even connected to the mouth.
Sight- They have very good eyesight. They have color vision, and large eye. They have good vision in dim light, and mirror-like layer in the back of the eye. The layer doubles the intensity of incoming light(enhancing light sensitivity). Their pupils can dilate and contract to control the amount of incoming light. Sharks that live deeper in the oceans usually have larger eyes than those that live near the surface.
Hearing- The dogfish shark is very sensitive to low frequency sounds and have good directional hearing. They have endolymphatic pores.
Electroreception- They have a social network of jelly-filled canals in their head called the ampullae of lorenzini that detect electric fields. This network lets the shark pick up weak electrical stimuli from the muscle contractions of animals. It also detects the magnetic fields, which some sharks may use in navigation.
Water Pressure-They can sense vibrations in the water using the lateralis system. This system is a network of neautomasts, which are vessels that run along a sharks body under the skin along the length of a shark. Many small pores open up on the skin detecting the intensity and direction of vibrations in the water. This system enables the shark to detect injured fish that are thrashing around in the water.
Food Capture- It is a step by step process. They sense the prey, stalk the prey, and then catch the prey. They mostly eat fish(anything they can get).
Digestion- Food moves from mouth to the j-shaped stomach where it is stored and initial digestion occurs. Unwanted items may never get past the stomach. The shark either vomits or turns its stomach inside out and ejects unwanted items from its mouth. They have much shorter intestines. They are spiraled. They have a long surface area, which requires food to circulate inside that short gut until fully digested.
Reproduction- There are 2-11 pups are in each litter. The pups are between 8-12 inches. The gestation period is 18-24 months after a winter mating. This is longer than an elephants or whales. Females reach maturity at 19-20 years of age. Their life span is 25-100 years old.
External environment-Their body temperature comes to match of their external environments. The can tolerate relatively high concentrations of urea in their bodies. They have osmolarity similar to that of their external environment, and therefore lose less water to their environment.
Internal Environment- They have cooperation of all of its cells. Their tissues and organs maintain homeostasis.
Gas Exchange- They have gills slits at sides of their head. The take in oxygenated water and put out de-oxygenated water. Gills are feathery, threadlike filaments. Have fewer but larger blood cells and its hemoglobin has twice the affinity for oxygen. It also maximize gas exchange through counter current exchange.
Circulation- They have 2 chambered heart. It is a S shaped tube that is located in the head region of the shark. Blood is pumped to the heart ten brachial arteries, and then to the capillaries in the gills. Then to different branchial arteries then through the tissues of the body, and then back to the heart.
Immune System- They are immune to almost all diseases. Sharks have small tooth like spikes instead of scales. Their tissue appears to have antibacterial properties.