The nares or external nostrils are located on the underside (ventral surface) of the rostrum anterior to the jaws. A nasal flap separates the incurrent from the excurrent opening.
How many nostrils does a dogfish have?
two nostrils
Spiny dogfish possess a conical shaped head and pointed rostrum. An anterior incur- rent nostril and posterior excurrent nostril were formed from a thin anterior nasal flap that separates the two nostrils (Fig. 3A). The incurrent and excurrent nostrils were wide and circular in shape.
How does a dogfish breathe?
Gills. The Pacific spiny dogfish has a unique system of ventilation. This type of dogfish has five gills on each side of their heads, but do not have gill covers like bony fish. The shark is able to breathe with these gills by swimming or staying in a current.
What structure is unique to dogfish?
A feature peculiar to our specimen, the spiny dogfish, is the presence of two spines, one immediately anterior to each dorsal fin. When captured, these sharks will arch their backs and attempt to pierce their captor with these long sharp spines.
Do dogfish sharks have gills?
The caudal fin is larger than normal, which makes the sharks maneuver through the water quickly and efficiently. The Pacific Spiny Dogfish has a unique system of ventilation. This shark has five gills on each side, but do not have gill covers like bony fish.
Does a dogfish have lungs?
The lungs are long, slender and saclike. They run along the dorsal sides of the pleuroperitoneal cavity and are attached to the body wall by the pulmonary ligament on the left side and on the right, the hepatocavopulmonary ligament that also supports the liver.
What is the function of the Nares on a dogfish shark?
The nares or external nostrils are located on the underside (ventral surface) of the rostrum anterior to the jaws. A nasal flap separates the incurrent from the excurrent opening. Water passes into and out of the olfactory sac, permitting the shark to detect the odors of the water.
How do dogfish sharks obtain oxygen?
The shark obtains efficient gas exchange through counter current flow. In this system, blood and water flow in opposite directions. Well-oxygenated blood leaves the secondary lamella and flows past water that has not yet encountered the secondary lamella. The water contains more oxygen than the blood.
How poisonous are dogfish?
Unlike virtually all other shark species, dogfish sharks possess venom which coats their dorsal spines; this venom is mildly toxic to humans and would be harmful if the shark were to be mishandled.
Can dogfish survive out of water?
They can survive out of water for 2-3 days. Their diet consists of anything that looks edible, but is mainly other fish. They prefer water bodies with heavy vegetation, but do inhabit clear water lakes.
What common feature is absent in the dogfish shark?
There is no notch on the upper caudal lobe and the lower caudal lobe is not well-developed. There is no anal fin on the spiny dogfish.
What are the characteristics of dogfish?
It consists 1st dorsal fins, Second dorsal fin, caudal fin, anal fin, and paired fins (anterior pair pectoral fins and posterior-lateral pelvic fins). The pelvic fins are simple but in males, the inner margin of the pelvic fins bears a pair of rod-shaped copulatory organs called clasper or myxipterygium.
Why is it called dog fish?
Sharks that are grouped into the dogfish family are so named because fishermen have observed these species chasing down smaller fish in dog-like packs.
Do dogfish sharks have tongues?
The oral cavity contains the tongue and teeth. The pharynx is the portion leading past the spiracle and five gill slits and also contains the tongue in dogfish.
Why do sharks bleed from gills?
As water passes over the gills, small capillaries allow oxygen to enter the bloodstream. The oxygenated blood is then pumped throughout the shark’s body. The blood then enters the heart and is pumped to the gills, where carbon dioxide is released and the process begins again.
What is the largest organ in the shark?
Liver
Liver: Taking up roughly 80% of the shark’s internal body cavity, the liver is the largest of sharks’ organs. The liver stores energy as dense oil which helps the shark with buoyancy, its ability to float.
Do sharks have 2 Hearts?
Sharks possess a single-circuit circulatory system centered around a two-chambered heart. Blood flows from the heart to the gills where it is oxygenated.
Do dogfish sharks have brains?
The brain in encased in membranes called meninges. In dogfish there is only a single meninx, which holds cerebrospinal fluid between it and the brain. The cerebrospinal fluid also circulates within the cavities of the brain and spinal cord.
Do sharks have hearts?
A shark’s heart is a two-chambered S-shaped tube, small in proportion to body size. Blood flows from the heart to the gills and then to body tissues.
How is the sharks nose different from our own?
How is the shark’s nose different from our own? The shark’s nose is only used for smelling their surroundings, not for respiration. Sharks use gills for respiration purposes. Humans use their nose for both breathing and smelling.
What is the purpose of the external nares?
anterior nares (or nostrils; exterior nares) allow air to enter the nose and pass into the nasal cavity. Individually, each opening is referred to as an anterior naris.
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