STEM-Zine Issue 1

CONTENTS CONTENTS 1 The Death of Creativity in the Nursing field 2 Descent to Extinction: The Downfall of the Spix's Macaw 3 The Truth of Being an Engineering Student 4 FFA: An Organization Dedicated to Agricultural Pursuits 5 Number Theory: Where the Fun Begins 6 How Humans Are The Catalyst To The Sixth Mass Extinction 7 Sargassum Invasion: a Caribbean nightmare 8 The Diversity of Young Bearing in Sharks

The Death of Creativity in the Nursing Field In this ever-evolving world we live in today, we are expected to develop and adapt accordingly in order to survive. Along with this, multiple facets of society are to follow suit, ranging from the government, laws and of course, education.

However, the latter seems to be facing challenges, with some fields slowly adjusting to the imminent changes and others, such as the Science, Technology, Engineering, and Mathematics (STEM) fields, more specifically the field of nursing, at a standstill. The rigid curricula, which have undergone minimal revision over the years, is doing little to foster creativity and innovation, stunting further development in those fields and leading to demotivation in students and teachers alike.

Due to time constraints and lack of flexibility in the structure of nursing education curricula, several educators face difficulty effectively delivering course material. Focus is taken from effective educator-student interaction which can foster skills and creative thinking and diverted towards addressing course content within a specific time frame. Though focus should not be taken away from the course material itself, other factors related to education, such as successful course delivery, teaching-learning methods, and rendering effective educator-student relationships need to be considered. Also, with the need to conform to constraints, educators do not get the opportunity to explore different teaching techniques, thus repressing their potential.

In addition, the needs of individual students are not being addressed appropriately, with students expected to learn in the same manner, typically in the traditional classroom format. This isn’t taking into consideration the different styles such as auditory and visual, which can be utilized

Hanna Regis

in order to increase understanding and thus facilitating generation of ideas.

In particular instances, a practical approach is required however, the timing and frequency of it isn’t sufficient. Usually, the first year of schooling is mostly dedicated towards learning theoretical aspect of nursing, which is understandable.

However, the practical approach is taught later on during schooling; a bit too late. Students are thrown into the clinical field at the end of the first year with very little knowledge on the performance of different nursing skills. This proves to be somewhat useless as not much is carried out by students and the experience is not as fruitful as it could be. In addition, veteran nurses often times fail to remain up to date with current nursing practice and are not open to new approaches. With this mindset, they are not keen on listening to students and newly graduated nursing alike, thus discouraging the application of new techniques and knowledge.

Changes need to be made in the structure of the education curricula in the nursing field, whether it be in the course delivery or the teachinglearning techniques utilized. The system must be viewed as multidimensional in order to achieve this; with the importance of all aspects of education being acknowledged. By doing so, innovative and revolutionary ideas may be developed and bigger strides may be taken in moving forward.

Image by Joseph Smit

Descent to Extinction

D e s c e nt t o E x t i n c t i on : The Downfall of the Spix’s Macaw Written by Amelia Kirk

Rio was a fun, family friendly film.

People of all ages enjoyed the story of the little blue macaw that couldn’t fly, so much so it got a sequel. Unfortunately for the Spix’s macaw, the bird that inspired Rio, there were no second chances. The bird has been on the IUCN Red List since 1988, when it was declared “threatened”, and less than a decade later in 1994 it was considered “critically endangered”. Despite various conservation efforts, that status has not changed.

Spix’s macaws have never been particularly commonplace in the wild, instead remaining a rare treat for those that mange to observe them in their natural habitat. However, the decline in their population to eventual extinction is far from a natural occurrence. They are another species victim to the Holocene extinction, the ongoing extinction event, of which humans are the driving force.

A deadly combination of habitat loss and trapping for pet trade may have been the cause for the downfall of this bird. The blue plumage of the macaw and its slightly smaller frame when compared to other macaws makes it an attractive bird, and as with most other exotic pet species, it’s attractiveness is likely what draws many people to desire to own them, as well as their ‘vibrant behaviour’. Despite it being a criminal offence to trade this bird commercially, Spix’s macaws are still owned as pets today and will fetch around £153,000 ($200,000) for a serious buyer. Over 90 individuals are believed to be held in captivity worldwide, including unregistered pets and those apart of official breeding programmes, in the hopes that a formal reintroduction can, one day, be attempted.

In November this year, an article was published in the journal Biological Conservation following an eight-yearlong study into the possible conservation status reclassification of many bird species. Among them, three species were reclassified as completely extinct (cryptic treehunter, Alagoas foliage-gleener, and poo-uli), and the Spix’s macaw as extinct in the wild. The last confirmed sighting of a Spix’s macaw dates back 18 years to 2000.

In 2016 there was a brief splash of hope when a lone bird thought to be our little blue macaw was filmed over the Caatinga area of Brazil by 16-year-old Damilys Oliveira. Unfortunately, it is difficult to declare videos such as these official examples of Spix’s macaw sightings, and since Oliveira’s video there have been no further reported sightings In the wild these birds depend on of the bird in the wild. woodland dominated by a spe-

cies of small tree (Tabebuia aurea), which grows to eight metres, for shelter. In addition to habitat reduction through deforestation, making it difficult for the birds to find adequate nest sites, the low height of the tree causes it to be easier for trappers to access and capture the ones that are able to nest successfully. Spix’s macaw trapping has always been excessive, and may have been what pushed their species to the brink of existance.

Yet still, there is one last remaining chance for the Spix’s macaw. If captive breeding programmes prove to be successful, we may be able to hope for the reintroduction of the bird to selected areas of Brazil by 2030.

This will only be possible with the cooperation of bird holders worldwide and the diligent monitoring of illegal trapping activity. As a large species that depends on exploiting land for agriculture and living environments, our effect on the wildlife of Earth is profound. Therefore, it is our own responsibility to ensure the protection of the animal species we affect. The Spix’s macaw, like others before, may eventually be lost to trapping, poaching, and loss of habitat if our current attitude to conservation continues. It is simply another creature, on the long list, that does not deserve to suffer for our own greed.

The Truth of Being an Engineering Student

Social media is great at making people think you’re living the “perfect” life. Posts of the fancy cappuccino that you drank at that niche coffee shop that one time, of the perfectly aligned highlighters and perfectly written notes that you definitely took during class, of the “totally-not-impractical” layout of your study materials - the facade that you’ve created for people to base their expectations of the life you live off of. And I, along with all the other unfortunately bright-eyed, optimistic, and gullible, incoming college freshmen, believed that studying would be all crunchy fall leaves and large sweaters, perfectly done messy buns and quiet all-nighters, straight and neat binders and perfectly highlighted notes. I believed that the aesthetics would come naturally, that that’s just how life was. Unfortunately, I was proven quite wrong. Especially in the engineering department.

Being determined to live that life full of aesthetics, I tried my best to take neat notes, keep my room clean, wake up early every morning, have 3 square meals full of healthy fruit and vegetables, make friends and hang out with them, go to sleep early… but I couldn’t do it. Being an engineering student, I quickly learned what kind of environment I had gotten myself into.

It’s not like what social media depicts at all. At least where I go to school, the crunchy leaves and large sweaters were more like flash floods and soaked socks, the perfectly done messy buns and quiet all nighters became haphazard ponytails and struggling to stay awake at 4am to finish an assignment due in 4 hours because “what’s proper time management?”, and the straight and neat binders and perfectly highlighted notes were actually papers thrown in a folder in a hurry and notes written with the same black pen for all my classes that would be organized and deciphered

Renee P.

at a later time in the day, week, month, because I just don’t have the time right now.

It meant that I had to do more math and physics than I was mentally prepared for. It meant that I had to work with more people in more group projects and assignments than I’d ever thought I’d be comfortable with. It meant that I would be breaking into classrooms in the library with my friends because we just wanted a quiet place to study since the library itself was packed. But it also meant that I’d be making memories in college that I wouldn’t have made if I had been studying another degree.

Engineering isn’t an easy major. It’s challenging, that’s for sure, but it’s also really rewarding. As a senior, for me to say that I’ve made it this far is an accomplishment. I feel as though I have actually gained useful knowledge during my studies as opposed to just memorizing right before the exam and forgetting hours later. It was - and still is - a lot of work, but I in my opinion, it’s worth every bit of effort. It’s fascinating to me, to see how the concepts I’ve learned in class are applicable to the real world in a truly physical sense. It’s not just that it can be applied, it’s that it has to be applied. The bridges I drive over to and from school, the refrigerator sitting in my dorm room, the way the power for the campus is generated, even the way fire sprinklers work - it’s all stuff that I’ve learned about and it’s all stuff that that has to and does exist in the real world.

Being an engineering student is spending late nights in the library classrooms studying for exams, and waking up before the sun comes up to finish homework. It’s spending too much money on starbucks, and spending even more time with your groupmates to finish that lab report. It’s an experience that I wouldn’t trade for anything else because if I wasn’t an engineering student, I wouldn’t be who I am today.

FFA: An Organization Dedicated to Agricultural Pursuits

Kayla W.

“...To practice brotherhood, honor agricultural opportunities and responsibilities, and to develop those qualities of leadership which an FFA member should possess.� This is the response posted to members who embody the persona of an emblem representing unity, labor, freedom, knowledge, and progress.

The National Future Farmers of America Organization dedicates itself to helping its students develop their skills in premier leadership, personal growth, and career success.

As such, the membership totals to 653, 359, including student members that range from chapters in middle school to high school and belong to 8,568 chapters in the United States, Puerto Rico, and the U.S. Virgin Islands. FFA functions on local, state and national levels through the ever-growing need for agricultural education. With a focus on the importance of agricultural education, the organization encompasses FFA, a mandatory student organization, classroom education, and a supervised agriculture experience, a year-long agriculture-related program, to provide leadership opportunities.

FFA, as a student organization, offers many benefits, such as scholarships, networking, travel, and fun in activities and other programs. To hone student skills, FFA offers a variety of career and leadership development events that range from agricultural communications, employment skills, floriculture, and poultry evaluation.

The organization was first established in 1928 and changed its name from The Future Farmers of America to the National FFA Organization to recognize the organization’s growing diversity in agriculture.

The organization has very important key dates in its history that have led to its growing diversity. In 1969, FFA membership opened up to girls. In 1974, Fred McClure was the first African American elected for a position at the national level. In 1976, Julie Smiley was the first female elected as vice president at the national level and in 1982, Jan Eberly became the first female president at the national level. In terms of a need for more diversity, Corey Flournoy was the first African American to hold an elected position of president at the national level.

As someone who is involved heavily with FFA and holds a position on a chapter level as the Reporter, I find that despite not wanting a career in agriculture, the organization allows me a safe haven where I can grow and improve in all aspects and areas of my life on a general basis.

Number Theory:

Where The Fun Begins Andrea Michelle When we talk about mathematics the first thing people do is imagine equations, derivatives, and all the things we learned during our last years of high school. We often forget to associate the image of mathematics with those easy things we learned at the early years of your life.

Instead it is strongly connotated with the pain, misery and frustration that accompany complex math homework. But

When did it start?

what if I were to tell you there’s beauty in maths, in the things we learned during our first years of elementary school?

Binomial coefficients, GCF and LCM, divisibility etc, are all well-know topics you might remember from your days in high school. These simple topics all belong under the umbrella concept of ‘The Theory of Numbers’.

It started around 300BC when it was proved by Euclid that there are infinitesimal prime numbers. Besides this he deduced the fundamental theorem of arithmetic: every positive integer factors uniquely as a product of primes.

Around 972A.D. the congruent number problem was made

by Arabs in which they find if a positive integer n is the area of a right triangle, all three of whose sides are rational numbers.

The square numbers are the numbers that can be arranged in the shape of a square: 1, 4, 9, 16, . . .

The triangular numbers are the numbers that can be arranged in the shape of a triangle: 1, 3, 6, 10, . . .

Numbers and Their Shapes

Every natural number n>1 can be expressed in an essentially unique way as the product of prime numbers.

The theory of numbers studies what is commonly called arithmetic.

It is built upon the set ℤ: (…,-2,-1,0,1,2,...) which consists of all positive and negative integers as well as 0. All the rules that make up the world we know start by these numbers so it’s only fair we have a whole area of mathematics dedicated to them.

On ℤ, there are two basic operations: addition (denoted by +) and multiplication (denoted by · or x or *). From them we can define two other operations on the same set ℤ: subtraction (denoted by −) and division (denoted by /). While addition, subtraction and multiplication are binary operations, i.e. operations were two elements of a set produce another element in the same set, division is binary for only certain values. With these simple operations we define all the rest of known arithmetics,

What is

Number Theory?

such as powers, limits, derivatives, etc.

If you think about it, there is so much beauty to all the things we have learned to do mechanically. Take the Pythagorean equation for example, whose simple concept, the addition of two squares makes another square - algebraically, is a key calculation for most architecture you see on your evening stroll. In geometry, we refer to the same concept by quoting that in a right-angled triangle the square of the hypotenuse is equal to the sum of the other sides.

Number Theory is the easiest area in mathematics to learn. Yet, although you live it every day, it can difficult to comprehend as most of it is based off abstract concepts.

We forget how fun, intriguing, and beautiful it’s ideas are and how they influence every aspect of our lives.

Wouldn’t it then only be fair for us to take time then, to study the whys of all the rules that make our world the way it is.

How? Why? The answer for these questions about equations that have simplified our lives so much lie in math.

Every even number bigger than two can be written as the sum of two prime numbers.

References Clark, W., & Hefferon, J. (2003). Elementary Number Theory.

Raji, W. (2016). An Introductory Course in Elementary Number Theory.

Sato, N. (2015). Number Theory Stein, W. (2009).

Elementary number theory. New York, NY: Springer.

.

ecosystems. In most cases native plants and animals are unable to compete with different invading species which puts them at risk for extinction. According to the Red List produced by the International Union for Conservation of Nature, out of the 170 extinct animal species with a cause of extinction on the list, invasive species contributed to the extinction of 91 species and cause the extinction of 34.

VI. Decreasing honeybee populations In the U.S, honeybee populations have gone from 5 million hives in 1988 to 2.5 million today, subtracting nearly half of the population we used to have 30 years ago. But it isn’t just the U.S; it’s global. The world has been experiencing a colony collapse since 2006. Although we are not entirely sure what’s causing this, the statistic could argue that the buildup of human developments may have caused major changes in the environment, causing this phenomenon. This is crucial to the path of life in the future, since honeybees are the source of one third of the food we consume today, and their dying out

will affect thousands of plants, thereby affecting food chains that lead all the way up to humans, potentially being the primary cause for the next mass extinction.

Population growth The rapid increase in human populations has brought along a whole other host of problems. The spurring start of the industrial revolution skyrocketed population growth and increased carbon emissions because of fossil fuel dependent developments, changing the makeup of our atmosphere. Along with this, species invasions and extinctions exploded correlationally with the excessive production of metal and plastic and then eventually along with the discard of such materials as well.

Pollution Two notable examples of pollution that push extinction rates higher are air and marine pollution. Air pollution can affect many plants, as shown in a study conducted by Carly Stevens, a student from the Open University in the U.K. Stevens studied areas with similar grassland plants affected by air pollution from emissions sourced from cars exhausts and intensive livestock farming, resulting in higher levels of nitrogen and ammonia. It was found that in areas with higher levels of nitrogen, plant variety was decreased compared to areas with lower levels of nitrogen. The study suggests that air pollution could affect plant diversity and their ability to flourish in areas with a higher concentration of air pollution which could eventually lead to the extinction of plant species if pollution grows to an extent that plants are unable to thrive. Marine pollution is also an issue, with

at least 690 species have encountering marine debris. Dumping waste into bodies of water kills many sea creatures due to them getting stuck and being unable to move or from ingesting the waste and then dying of starvation. Indirect pollution can also occur through fertilizers that farmers use on land.

The fertilizer end up in groundwater and streams that lead into larger bodies of water. The high nitrogen content and nutrients in these fertilizers can trigger algae blooms that use up all of the oxygen in the water, leaving the area barren and uninhabitable for the marine life that once flourished there.

“The lesson and the warning are

Although humans are greatly affecting factors that could lead to a sixth mass extinction, it’s important to understand that, thankfully, we haven’t reached the point of that yet, meaning that it is still not too late to start making changes. Our existence on earth has definitely brought a change, but it doesn’t have to be a negative one in the end. We still have time to take care of the major issues that cast dark shadows like extinction over the future and to make improvements, grow, and slow down negative events instead of speeding them up.

Preparing for the future will require innovation, thought, and enough intellectual curiosity to fuel new and creative thinkers to lessen our impact. This is not a time to be selfish. We made it to the top, and we now hold responsibility over the future of this planet.

there for all to see.”

Sandra Knapp from the Natural History Museum.

Article Authorship and Design

By H.F.

In the past few months the mats of drifting sargassum covered with berry-like sacs have become so numerous in the Caribbean Seas they’ve been called a ‘natural disaster’, the 'greatest single threat', ‘the cause of a socioeconomic disaster’ and many other adverse names by newslines telling you not to visit the Caribbean beaches. This massive sargassum flow is becoming a major challenge for tourism-dependent countries. But how can we fix this?

First of all, what is Sargassum?

At first glance, beach-lovers might view it as nothing more than a foul-smelling annoyance. Sargassum is a floating invasive brownish algae that generally blooms in the Sargasso Sea, a 2 million-square-mile (3 million-square-kilometer) body of warm water in the North Atlantic that is a gyre for floating algae and major habitat and nursery for numerous marine species. Massive strandings of sargassum have been invading beaches since 2011 but this year's quantities are almost double as those of 2016.

Where is the invasion happening?

Right now the countries receiving major socio economic threats by the algae invasion range from Dominican Republic in the north, to Barbados in the east, and Mexico's Caribbean resorts to the west. In 2015, large algal mats inundated not only the Caribbean but also the American* and the west African coastlines in unprecedented amounts.

And why is it there?

“Short answer: we don't exactly know.”

However there are some educated guesses and theories that can guide us to the answer.

1st - Global warming: Some sources say rising temperatures definitely help the algae “bloom” but it's not enough alone to make it thrive. Other researches say global climate change might have forced the Sargasso Sea to move further south, bringing the seaweeds closer to the Caribbean Sea A study from the journal of the European Geosciences Union in 2016 also indicates that ocean acidification and eutrophication have a promoting effect on the algae.

2nd - Nutrient-rich waters These land-based nutrients and pollutants (Including nitrogen-heavy fertilisers and sewage waste) act as fertilizer for the seaweed creating optimal conditions for their growth. Researchers consider the increased intake of nutrient-rich Sahara dust (including Fe, K and phosphate) as one of the major drivers facilitating the growth of algae in the sea.

Another hypothesis attributes the Sargassum invasion to nutrient overload resulting from deforestation of the Amazon basin in Brazil In fact, because of deforestation, the amazon river spoof tons of organic matter and nutrients to the sea thus promoting excessive growth of algae.

3rd - Disturbance in liquid boundaries: Winds, storms, and spiraling currents help disperse Sargassum throughout the world’s oceans.

Travel Agent learned in Barbados, changing climate and wind/ocean patterns are what seems to be carrying the seaweed to the destinations.

Related studies about the origins of this sargassum invasion are very scarce. It’s difficult to come up with a solution when we’re blind to the root of the problem.

Is it doing anything positive?

Yes! The once floating mats were home to (and source of food for) a huge variety of sea life (like tuna, billfish, eels, shrimp, crabs and sea turtles all use the algae to spawn, feed or hide from predators). In fact, several creatures, like the Sargassum fish (a type of frogfish), are born, reproduce, and die solely within this environment. Sargassum also is a prime nursery habitat for a diversity of large fish, such as mahi mahi (a.k.a. dorado dolphin), sailfish, jacks, amberjacks, etc.

To add on, as stated in the Defenders of Wildlife in 2010, “Sargassum is also a vital nursery for newly fledged sea turtles that are especially vulnerable to ocean-going predators” Under certain conditions, the presence of algae on the beaches can help fight beach erosion.

Why do people want it out?

It is as best put by scientist Ine van Tussenbroek “An ecological disaster in the short term and by extension also a socioeconomic disaster because all the industry here depends on tourism.”

At high concentrations, Sargassum may negatively affect marine flora and fauna located near the coast.

Brian Lapointe, a sargassum expert at Florida Atlantic University, says that while the sargassum washing up in normal amounts has long been good for the Caribbean, severe influxes like those seen lately are ``harmful algal blooms" because they can cause fish kills, beach fouling, tourism losses and even coastal dead zones.

Sargassum invasion also affects oxygen levels in the water, brings contaminants and other microorganisms to the beach, reduces light, oxygen (hypoxia or anoxia) and pH (ocean acidification), changes the ecological balance of coral and causes beach erosion.

And when it decomposes in water it can promote blooms of harmful bacteria and microbes which can cause serious skin irritation.

Then there is tourism, all countries affected by the Sargassum invasion are experiencing unforeseen cancellations during the heavy tourist season. Piles of seaweed as high as three meters are paralyzing tourism and fishing. State authorities said last week that 80,000 cubic meters of the seaweed had been removed between June 22 and July 22 (2018) on beaches in various parts of Mexico (Cancún, Solidaridad, Tulum, Puerto Morelos, Othón P. Blanco and Cozumel). The mayor-elect of Solidaridad, Quintana Roo, estimates that tourism has dropped as much as 35% due to sargassum seaweed washing up on a 480-kilometer-long stretch of otherwise pristine Caribbean beaches.

Worsening seaweed influx could become a chronic dilemma for the globe's most tourism-dependent region.

"This has been the worst year we've seen so far. We really need to have a regional effort on this because this unsightly seaweed could end up affecting the image of the Caribbean," - Christopher James, chairman of the Tobago Hotel and Tourism Association.

What are we doing about it?

What should we be doing about it?

In mexico, they’re planning to create a governmental agency dedicated to addressing the sargassum crisis. Officials are authorising emergency money to fund cleanup efforts and clear stinking mounds of seaweed that in some cases have piled up nearly 10 feet high on beaches, choked scenic coves and cut off moored boats. Mexican authorities recently said they will spend about $9.1 million and hire 4,600 temporary workers to clean up seaweed mounds accumulating along that country's Caribbean coast.

But Cleanup efforts by work crews may also worsen beach erosion. After the crews pick up the decaying seaweed they integrate it into dunes along the shoreline, bury it or dispose of the material in the landfill. Also when removed from the beach, heavy machinery tends to compact the sand (this can affect turtles nesting, e.g.) and remove both sand and nutrients from the shore, which can lead to beach erosion.

I believe it's obvious enough not only by this consequence but by all the other ones i'm sure you have seen and lived that we should work to mitigate climate change.

Options that have been taken into action by several countries include placing nets offshore to contain the seaweed before it reaches the beaches. The weed would then be collected by boats. Another option would be to use tractors to collect the seaweed after it washes up on the beaches.

Senator Beristain said beach clean-ups should occur daily in the state to remove the sargassum. .

A study was made in feb of this year to evaluate the potential to manage the invasive species sargassum using composting and to test the quality of the resulting compost. The final compost products were of equal or higher quality to current compost standards.

Apart from that we should be doing research, as we dont even now the full extent of the negative impacts that come with this invasion. Martha GarcĂ­a a UNAM researcher, said that no studies have been done about the effect of sargassum on human health We should also invest in research about all the potential uses of sargassum in areas as the medical and pharmaceutical. There have been studies about how the composting and waste management industries can use sargassum as a feedstock to create a desirable compost product which could be used in the horticulture and agriculture industries. Other studies suggest Sargassum can be converted to biogas via anaerobic digestion.

Biogas made predominantly of methane, has a high-energy value, that can be used to meet many of our energy needs.

There is a need for further research into the all the potential Sargassum have outside of the beach as well as their strandings in the Caribbean to better understand the trends and patterns of this seaweed and how we can manage this invasive species.

As an individual you should educate yourself, demand change and vote for an official who is equally (or preferably more) educated in the subject and if you, like me, cannot vote; educate yourself, educate those who can vote and demand change.

HOLLY VAUX

Photo by Jared Rice on Unsplash

Diversity of Young Bearing in Sharks

For more than 400 million years sharks have dominated the oceans as a near unmatched predator. Terrifying and dangerous, yet majestic and captivating, these creatures have always been on the forefront of human fears and scientific interest.

Despite the persistent interest in sharks, many of the aspects of their life cycles are unknown; however, one commonly known fact is that sharks are long distance swimmers making them more difficult to study and understand. They often swim thousands of miles over their lifetime, because of which keeping them in captivity prevents tracking genuinely healthy behaviours of sharks, especially reproductive and birthing.

Monitoring shark reproduction and birth in the wild has often led to inconclusive results due to stress responses to capture such as spontaneous abortions and death due to being caught in nets.

Yet, after many years of monitoring, three main young bearing methods have been identified: viviparity, ovoviviparity and oviparity. This diversity of birthing techniques seen in sharks is not replicated in any other class of organisms, making this feature incredibly fascinating.

Sharks reproduce much the same as humans via internal fertilisation, where sperm and egg fuse within the reproductive tract of the female; however, this is where the commonality ends for a lot of shark species. Once fertilised, the embryo develops and is birthed in one of the three previously mentioned methods which is dependent on the evolutionary history of the species.

Viviparity is a young bearing method predominantly seen in mammals, making its presence in some shark species strange as their evolutionary split from each other was a long time ago on an evolutionary time scale. It is mainly seen in the requiem sharks (Order: Carcharhinidae) which includes the bull shark (Carcharhinus leucas), the grey reef shark (Carcharhinus amblyrhynchos), and the spinner shark (Carcharhinus brevipinna).

Viviparity is when an organism reproduces by internal fertilisation and the young develops within the uterus until being live born. With this method, the offspring is connected to the mother via a placental link, providing it with nutrition for development before being live-born. If the offspring is not provided with this, it is unable to reach a developmental stage that would allow it to survive alone in the wild once born and since sharks do not invest into parental care this is essential for the success of the offspring.

Oviparity is the only young bearing technique in sharks where they embryo develops outside of the mother in egg-cases, rather than internally. It only occurs in three shark families; Heterodontidae, Scyliorhinidae and Hemiscylliidae. The eggs are fertilised internally and are enclosed into collagen-based egg-cases, often known as a mermaid’s purse, which provides the embryos with nutrition and protection during their development outside of the mother.

These egg-cases take a large amount of energy to create, but once the energy has been invested into their creation the mother is able to leave them and hunt to sustain herself without having to continuously spend energy to maintain the development of her offspring through a placenta.

The security of her embryos is not a worry for the mother since the egg-cases are attached onto substrates on the ocean floor using tendrils or an adhesive substance, allowing the embryos to develop safely in an area inaccessible to predators.

Ovoviviparity is the most common young bearing method seen in sharks, however, this is due to the gaps in biological knowledge regarding shark young bearing, since ovoviviparity is used to classify birthing methods in sharks that neither fit into viviparous or oviparous classification. Generally, ovoviviparity is when the young develop within an eggcase in the females, which will then hatch into her reproductive tract to be live born.

Internal egg-cases means a placenta is not needed to provide nutrition to the offspring; instead offspring will gather nutrition from the yolk of the egg-cases, by consuming the unfertilised eggs or by eating their lesser developed siblings in the reproductive tract (intrauterine cannibalism).

The number of shark species that display ovoviviparity is currently up for debate, since there is no way to observe the early stages of development after hatching from the egg cases in live sharks. The induced abortions that occur when females are caught to be observed has led to misunderstandings of which species are ovoviviparous and viviparious, and research on this topic continues to this day.

STEM-Zine

CREDITS

EDITOR-IN-CHIEF Ashima Mugibur Raghman CO-MANAGER

Kayla Woods

HEAD OF DESIGN

Isabelle Zhu

Design Team Eva Heitmann Levenson Hana Sofía Velásquez

Writers 1.

2.

3.

4.

5.

Amelia Kirk Kayla Woods Hana Renee P Andrea Michelle Marketing Team Velasquez Ashima Mugibur Raghman 6. Hanna Regis 7. Holly Vaux Kayla Woods 8. Alexandra Dalmau Isabelle Zhu