Reproduction Mating season usually occurs during the winter. During the breeding seasons, males of various stingrays use their “ampullae of lorenzini” to sense certain electrical signals given off by other female counterparts before potential copulation. When the female is found within site, the male courts the female until he is able to bite at her pectoral disc (pre-copulatory biting). In this process the male bites off the female’s pectoral fins and in process, replaces one of his two claspers into her valve or cloaca. The clasper then transfers the sperm into the female’s oviduct where the egg is fertilized until the birth of the babies. All female Stingrays are internal fertilizers and therefore undergo a process called ovoviviparity. …show more content…
This includes all 800 species of rays, skates, sharks and chimaeras (Katie Birkett, 2014). Based on fossil remains, it has been known that this class of fish have been around since the Paleozoic period (approximately 250 million years ago), however theories have accumulated that the adaption of the flattered bodies (alike stingrays) had only occurred around 100 million years ago (approximately around the Lower Jurassic Period). Before the stingray’s existence, stingrays had in fact been evolved from sharks. This process took nearly 150 to 250 million years to complete for the first ever rays came upon this earth and also the reason why stingrays and sharks share a common ancestor within elasmobranch fishes. As this occurred, the development of their body shape and the loss of body area enabled early rays to hide and camouflage very discreetly against predators and to its pray. In addition, the process of their evolution introduced a new convergent evolution adding the additional venom stingers we all see in stingrays today and altering the way they reproduction from laying eggs to live birth. Currently there are two types of stingrays: ones in the family dasyatidae (stingrays) and ones in the family potamotrygonidae (river
The Pastinachus solocirostris, also known as the Roughnose Stingray, is from the Pastinachus genus of stingrays in the family of Dasyatidae. It is found generally in shallow waters of mangroves off of Sumatra, Borneo, and Java. They grow to 72 centimeters across, and is characterized by their pointed snout. The fin disc of the Roughnose Stingray is wide, diamond-shape, and rounded on the corners. They have about 20 upper teeth and 25 lower teeth, with five papillae on the floor of the mouth. Like other stingrays, they are reproduced in embryos inside the mother, nourished by yolk, and then later with uterine milk from the mother. The Roughnose Stingray are listed as endangered, prone to being victims of bottom longline fisheries, used for its
Reproduction usually occurs once a year for hammerhead sharks. Male hammerhead sharks start to bite the female hammerhead sharks when they are ready to mate. Female hammerhead sharks give birth to their cubs in the warm water. They are able to have 12-15 cubs at once. Not all cubs will make it out of birth from the mother. The female hammerheads immediately leave the pups alone to take care of themselves. A good percentage of the cubs will survive after birth and it is unusual for all cubs to survive.
The Dasyatis americana or Southern Stingray has a disk or diamond shaped body more at an angle. They have sharp spines on their face. Its usual weight is 97 kg. The stingrays symmetry is bilateral. The main size is 200 cm. The colorings or markings are a dark grey in younger stingrays. Green and brown are the colors of the adults.
They exhibit a polygynous mating system, which means they have one-male and multi-female groups. The male’s large home ranges envelop the home ranges of several females. The males will mate with all the females in their home range and even some in extending home ranges. Females will also mate with members of different home ranges. The two remain together for several days while mating and will copulate several times in that period. Litters are usually fathered by one male, and the males will defend and mark their territory while mating. Females will mate every other year from May to August. They will stay in heat from June to August, and most mating will occur in June or July. Most interestingly females display a delayed implantation where the embryo is not implanted immediately at copulation but actually waits in diapause for about six months. Fertilized eggs develop to the blastocyst and will remain there until implantation to the uterine wall which typically occurs in the months from December to February. This means pregnancy may last anywhere from 120 to 272 days. Which will depend on when the embryo is fertilized and when it is implanted. Parturition is perfectly timed for the optimum survival of their young, which is usually when the most food is available. Females build snow-dens to birth and nurse their young. They typically have two dens, a natal den for giving birth and then when this den is
The cownose ray (Rhinoptera bonasus) is found in open Atlantic Ocean waters from Western Africa to the Northeastern United States and parts of the Caribbean. Cownose rays are a migratory species on the Atlantic Ocean, that returns to the Chesapeake Bay each summer to mate. These animals prefer warm waters up to depths of 72 feet, where they can find bottom dwelling lobsters, crabs, and small fish for prey. The cownose ray possess adaptations to easily locate, kill, and eat its prey. One such adaptation is the electroreceptors found on the ray’s snout. These creatures cruise for prey over soft mud and sand bottoms, until they sense electrical stimuli from organisms through these electroreceptors. The ray will then stir up mud or sand by fluttering
For this discussion, I chose to examine the reproductive nature of mountain lions and hammer head sharks. Mountain lions are solitary cats that live in various mountainous regions of north and south America, but a male and female come together socially in order to mate during the 3-10 day estrus period. Due to their solitary nature, mountain lions rely on scent marking in different territory as well as a mating call of the female in order to initiate the potential for sex. Typically, when a male and female find each other; they spend several days together during the mating period and he may hunt for her and run mating circles around her. Mountain lions are polygynous and both the males and females will mate with multiple individuals throughout
Between 1999 and 2004, researchers collected tissue samples from the “fins, muscles, or liver” of scalloped hammerheads. The samples were obtained via fishing or fish markets across multiple ocean basins, including “Pacific: Baja California, Pacific Panama, Hawaii, the Philippines, Taiwan, and eastern Australia; Indian: Thailand, western Australia, Seychelles, and South Africa; Atlantic: Western Africa, Brazil, Atlantic Panama, Gulf of Mexico, and east Coast USA” (K.M. Duncan et al. 2240). It is important to note that the researchers also retrieved samples from juvenile scalloped hammerheads that dwelled in separate feeding areas from the adults where, and this is because there was likely to be overlap between breeding populations within the
In insect species with indirect sperm transfer, sperm is packed in a spermatophore that is either externally attached to the female 's genital opening or introduced into her bursa copulatrix. Sperm transfer is not immediate in these species, and consequently mate guarding has been suggested to function as a mechanism of guarding sperm until it is released from the spermatophore into the female (i.e. spermatophore guarding). Spermatophore guarding is relatively common in insect species with external spermatophores (e.g. Orthoptera; Alcock 1994; Simmons 2001), but supposedly absent in species with internal spermatophores and rapid sperm release (Simmons 2001). This study focuses on two hypothesis associated with mate guarding a tactic of many species that adjust their reproductive behaviour according to the apparent risk of sperm competition. The phenomenon of mate guard to consider sperm competition levels and evolution of internal spermatophore guard is wide spread in insects and other animals. We analyse two hypothesis one the rival exclusion followed by the next spermatophore renewal hypothesis. Results showed that as rival was introduced to the arena of mating of the distinctive original male (guard) in many cases showed a strong aggressive behaviour regardless of whether successively avert the rival. In the second hypothesis certainly majority of the incidents showed an attempt of
The Lionfish is considered “one of the most aggressively invasive species on the planet”; there were no enemies within the Atlantic as none of the fish in this area had seen a Lionfish before. They wouldn’t realize that the Lionfish was in fact a cold predator, with extremely effective venomous spines, and had no enemies to limit its own population growth. They reproduce year round and fifty thousand eggs are released on a three day interval from mature females. The warm Gulf Stream aided their cause, as it’s water carried their eggs and larvae North, and
Obviously a very fierce animal, the skate, related to the ray, has special adaptations that can allow it to be protected from predators and to perform actions with ease. Seeking and consuming prey with ease, the skate has its mouth on its underside and it can eat prey that is hiding in the sand below it. Quickly swimming away from predators or to attack prey, the skate also has tiny teeth-like structures on its skin. The FLMNH Ichthyology Department reports, “The skin feels exactly like sandpaper
Throughout the poem, Pages Matam explores the key ideas and issues of victim-blaming and silencing victims due to society’s taboo of speaking out about sexual assault along with the foundations of rape culture. Matam effectively outlines the harmful idea that, your beauty leads to sexual assault which society inflicts upon victims, as a constant motif throughout the poem in the lines “Tell Elizabeth Fritzl, how pretty the flame of her skin was”, using sophisticated imagery within an allusion to explore this idea, comparing the providing an evidence-base to further support his argument and perspective. This idea is further reinforced in the repetition used in “Tell my 11th grade student, Lauren, that she wanted it, her beauty had them coming’
Sharks, have been on earth for 400 million years, making them older than dinosaurs, and they have lived on earth massively longer than humans. Shark culling has been witnessed since the late 1960’s by Australian’s because of a fatal shark attack on two males at that time.
Women in the 1920’s were expected to keep out of the public eye. They were not allowed to vote, or serve on juries. Legally, they were supposed to be subordinated. Women did not have the same rights as men pertaining to their political involvement. Because of this unfair inequality towards them, women decided to take a stance. In 1848 the movement for women’s rights was organize on a worldwide status. In July, Elizabeth Cady Stanton and Lucretia Mott created the first women’s rights convention in Seneca Falls, New York. More than 300 people (women, a couple of men and african americans) attended. Their belief was that women should be provided with better opportunities revolving around education and employment, and that they deserved to have a voice in their government. Elizabeth Cady Stanton composed a “Declaration of Sentiments” document, influenced from The Declaration of Independence, which stated: “We hold these truths to be self-evident: that all men and women are created equal; that they are endowed by their Creator with certain inalienable rights; that among these are life, liberty, and the pursuit of happiness.” Women believed they should have a right to vote. However, after this assembly, the idea of a woman being able to vote was teased in the press, which lead delegates to take back their support.
Sharks have been in our oceans for almost 450 million years. Those millions of years of evolution have allowed many different shark species to develop abilities, and to become perfect predators.
What Music Means to Me Music is a very important piece to our world. In every culture, music depicts a unique aspect to religion, celebration, and everyday life. The wide variety of different genres of music express emotion and character to us as individuals. It is everywhere on the planet, and has a different meaning in every culture. To me, music is a language.