Spiracles Aid in Breathing on Fish, Whales, and Insects

Spiracles Aid in Breathing on Fish, Whales, and Insects Spiracles are breathing openings found on the surface of insects, certain  cartilaginous fish  such as certain species of  sharks, and stingrays. Hammerheads and  chimeras dont have spiracles. In fish, spiracles are composed of a pair of openings just behind the fishs eyes that allow it to draw oxygenated water in from above without having to bring it in through the gills. The spiracles open into the fishs mouth, where water is passed over its gills for gas exchange and out of the body. Spiracles aid fish in breathing even when they are lying on the ocean bottom or when theyre buried in the sand.   Evolution of Spiracles Spiracles likely evolved from gill openings. In primitive jawless fish, spiracles were simply the first gill openings behind the mouth. This gill opening eventually separated as the jaw evolved out of the structures between it and the other gill openings. The spiracle remained as a small, hole-like opening in most cartilaginous fish. Spiracles are useful for the types of rays that bury themselves in the ocean bottom because they allow them to breathe without the aid of exposed gills. Primitive bony fish with spiracles include the sturgeon, paddlefish, bichirs, and coelacanth. Scientists also believe  that spiracles are associated with the hearing organs of frogs and some other amphibians. Examples of Spiracles Southern stingrays  are sand-dwelling sea animals that use their spiracles to breathe when they are lying on the ocean bottom. Spiracles behind the rays eyes draw in water, which is passed over the gills and expelled from its gills on its underside.  Skates, cartilaginous fish  that have a flat body and wing-like pectoral fins attached to their head, and stingrays sometimes use spiracles as their primary method of breathing, bringing oxygenated water into the gill chamber where it is exchanged for carbon dioxide. Angel sharks are large, flat-bodied sharks that bury themselves in the sand and breathe through their spiracles. They lie in wait, camouflaged,  for fish, crustaceans, and mollusks and then lunge to strike and kill them with their jaws. By pumping water in through their spiracles and out through their gills, these sharks can absorb oxygen and eliminate carbon dioxide without constantly swimming, as more mobile sharks must do. Insects and Animals  With Spiracles Insects have spiracles, which allow air to move into their tracheal system. Since insects dont have lungs, they use spiracles to  exchange oxygen and carbon dioxide  with the outside air. Insects open and close their spiracles through muscle contractions.  Oxygen molecules then travel via the insects tracheal system. Each tracheal tube ends with a tracheole, where the oxygen dissolves into the tracheole fluid. The O2  then diffuses into the cells. The blowhole of the  whale  is also sometimes called a spiracle in older texts. Whales use their blowholes to take in the air and dispel carbon dioxide when they surface. Whales have lungs like other mammals rather than gills like fish. They have to breathe air, not water.

Battle of South Mountain - Battle of South Mountain Civil War

Battle of South Mountain - Battle of South Mountain Civil War Battle of South Mountain - Conflict: The Battle of South Mountain was part of the 1862 Maryland Campaign during the American Civil War. Battle of South Mountain - Date: Union forces attacked the gaps on September 14, 1862. Armies Commanders: Union Major General George B. McClellan28,000 men Confederates General Robert E. Lee18,000 men Battle of South Mountain - Background: In September 1862, Confederate General Robert E. Lee began moving his Army of Northern Virginia north into Maryland with the goal of severing the rail lines to Washington and securing supplies for his men. Dividing his army, he sent Major General Thomas Stonewall Jackson to capture Harpers Ferry, while Major General James Longstreet occupied Hagerstown. Pursuing Lee north, Union Major General George B. McClellan was alerted on September 13, that a copy of Lees plans had been found by soldiers from the 27th Indiana Infantry. Known as Special Order 191, the document was found in an envelope with three cigars wrapped in a piece of paper near a campsite recently used by Major General Daniel H. Hills Confederate division. Reading the orders, McClellan learned Lees marching routes and that the Confederates were spread out. Moving with uncharacteristic speed, McClellan began putting his troops in motion with the goal of defeating the Confederates before they could unite. To expedite passing over South Mountain, the Union commander divided his force into three wings. Battle of South Mountain - Cramptons Gap: The Left Wing, led by Major General William B. Frankin was assigned to capture Cramptons Gap. Moving through Burkittsville, MD, Franklin began deploying his corps near the base of South Mountain early on September 14. At the eastern base of the gap, Colonel William A. Parham commanded the Confederate defense which consisted of 500 men behind a low stone wall. After three hours of preparations, Franklin advanced and easily overwhelmed the defenders. In the fighting, 400 Confederates were captured, most of who were part of a reinforcement column sent to aid Parham. Battle of South Mountain - Turners Foxs Gaps: To the north, the defense of Turners and Foxs Gaps was tasked to the 5,000 men of Major General Daniel H. Hills division. Spread over a two mile front, they faced the Right Wing of the Army of the Potomac led by Major General Ambrose Burnside. Around 9:00 AM, Burnside ordered Major General Jesse Renos IX Corps to attack Foxs Gap. Led by the Kanawha Division, this assault secured much of land south of the gap. Pressing the attack, Renos men were able to drive Confederate troops from a stone wall along the crest of the ridge. Exhausted from their efforts, they failed to follow up this success and the Confederates formed a new defense near the Daniel Wise farm. This position was reinforced when Brigadier General John Bell Hoods Texas Brigade arrived. Re-commencing the attack, Reno was unable to take the farm and was killed in the fighting. To the north at Turners Gap, Burnside sent Brigadier General John Gibbons Iron Brigade up the National Road to attack Colonel Alfred H. Colquitts Confederate brigade. Overrunning the Confederates, Gibbons men drove them back up into the gap. Widening the assault, Burnside had Major General Joseph Hooker commit the bulk of I Corps to the attack. Pressing forward, they were able to drive the Confederates back, but were prevented from taking the gap by the arrival of enemy reinforcements, failing daylight, and rough terrain. As night fell, Lee assessed his situation. With Cramptons Gap lost and his defensive line stretched to the breaking point, he elected to withdraw west in an effort to reconcentrate his army. Aftermath of the Battle of South Mountain: In the fighting at South Mountain, McClellan suffered 443 killed, 1,807 wounded, and 75 missing. Fighting on the defensive, Confederate losses were lighter and numbered 325 killed, 1560 wounded, and 800 missing. Having taken the gaps, McClellan was in prime position to achieve his goal of attacking the elements of Lees army before they could unite. Unfortunately, McClellan reverted to the slow, cautious behavior which had been the hallmark of his failed Peninsula Campaign. Lingering on September 15, he provided time for Lee to reconcentrate the bulk of his army behind Antietam Creek. Finally moving forward, McClellan engaged Lee two days later at the Battle of Antietam. Despite McClellans failure to capitalize on the capture of the gaps, the victory at South Mountain provided a much needed victory for the Army of the Potomac and helped to improve morale after a summer of failures. Also, the engagement ended Lees hopes for staging a prolonged campaign on Northern soil and put him on the defensive. Forced into making a bloody stand at Antietam, Lee and the Army of Northern Virginia were compelled to retreat back to Virginia after the battle. Selected Sources Son of the South: Battle of South MountainCWSAC Battle Summaries: Battle of South Mountain