Answers: 1.Circulatory system-pumping blood to and from the body and lungs with the heart 2.Digestive system-digestion and processing food with salivary glands, esophagus, stomach, liver, gallbladder, pancreas, intestines, rectum, and anus.
During the tie, the male turns around so the dogs are back to back and can defend themselves. The tie typically lasts 20 to 40 minutes. It may be just a few minutes, and dogs can mate successfully without becoming tied at all. The evolutionary reason for the tie is unknown, but it's assumed that if a male dog is tied to a female, it prevents other males mating with her. Unwanted Mating.
The method of tying fishing hooks was also investigated and a difference in catch rate between tying a circle hook versus snelling a circle hook was determined to be around 20% in favor of the snell knot. See the diagrams below on how to tie a fishing knot to attach the hook to the trace. Snelled fishing hooks. Besides improved catch rates, the snell knot takes only seconds per hook to tie. The resulting attachment is one of the strongest fishing knots around, whereas tying to the eye of the hook weakens the trace by as much as 40% (depending on the knot used and the skill of the fisherman tying the knot).