Megan+Tiwold

Adam Struss & Megan Tiwold =__**Summary**__= The Spiny Dogfish has placoid scales to reduce friction in the water so it can swim faster. It has two unpaired dorsal fins, two paired pectoral fins and two paired pelvic fins. The specie has a modified first gill slit behind their eye. Which serves for water intake. Has five pairs if external gill slits for breathing. Their mostly used for scientific dissection.

=**__Anatomy and Physiology__**= Average length of the Spiny dogfish is 75 to 105 centimeters. They can weigh up to 9 kilograms. The shark differs from other sharks because they have spots on their back called the lateral line canal, these are used as sensory receptors for location and orientation. This shark also has something called claspers. Claspers are on males only; modified capulatory organs located at the median border of each pelvic fin. These are used for sexual reproduction.

= = = = = = =Head= = = = = == =Trunk= == = = = = = = =Tail= == =__**Taxonomy**__= = = Phylum- Chordata = = = = Subphylum- Vertebrata Superclass- Pisces Class- Chondrichytes Order- Elasmobranch Genus- Squalus Species- acanthias =**__Ecology__**= Spiny dogfish inhabit the shelf and upper slope waters in depths up to 4,050 feet, but most are found in waters less than 1,150 feet deep. Spiny dogfish are common in inland seas, such as San Francisco Bay and Puget Sound, and in shallow bays from Alaska to central California. Males are generally found in shallower water than females, except for pregnant females that enter shallow bays to pup. Immature juveniles tend to inhabit the water column near the surface and are not available to the targeted fishery until they mature and descend to the bottom. Subadults are found on muddy bottoms when not found in the water column. Adults live on the bottom.
 * Notochord
 * Dorsal Neural tube
 * Vertebral Column
 * Fish
 * Exclusivelyaquatic
 * Fish with a cartilaginous skeleton
 * Fish with placoid cells
 * Contains sharks rays and skates
 * Scales
 * Spines

=**__Reproduction__**= Clasper

The specie reproduces sexually. The male hooks on with it claspers so the female shark doesn't flee. The female produces live offspring.

=__Importance and Relationship with humans__=

Their mainly used for science and dissection. In this sharks liver there's an oil named squalene which is used in a lot of anti aging creams.

=__Bibliography__=

Mrs. Miller's anatomy notes packet