The Scalloped Hammerhead – Scorpio

General facts About Sharks.

For decades, the Shark has been viewed as the greatest threat to ocean safety. It is the most feared fish in pop culture, with images of it baring its teeth- circling unsuspecting humans. Because we have painted these creatures in such a negative light, it’s hard to perceive them as objects of prey. The truth is, Sharks are dangerous, but not as dangerous as their most prolific hunter: humans. As a matter of fact, 97% of the 500 species of Shark pose no threat to humans whatsoever, although humans hunt and kill 100+ million sharks every year! This is substantially more than the average of 8 people killed by sharks every year.

Also known as Selachimorpha, Sharks are a prolific ancient species of fish. The earliest ancestors of these creatures date back 400 million years ago! Since then the size and demeanour of these creatures have varied greatly: ranging from the smallest Shark, the Dwarf Lantershark (only 17cm), to the Whale Shark (the largest fish in the ocean).

Sharks live in all oceans and seas, with some that can live in both salt and freshwater! It’s even more surprising to find that some sharks can exist purely in freshwater! Evolution has benefited this species greatly, allowing them to dominate oceans and inlets.

Introduction:

The Hammerhead Shark belongs to one of 8 families of Shark in existence today. These 8 “orders” categorize 500 different species of Shark within their families. The Hammerhead is from the Carcharhiniformes family, which houses 10 families, these include: The Great Hammerhead.  The Scalloped Hammerhead. The Smooth Hammerhead. The Scalloped bonnethead. The Whitefin Hammerhead. The Carolina Hammerhead. The Scoophead. The Bonnethead. The Small Eye Hammerhead. The Winghead.

This shark is difficult to understand from a scientific perspective, as its body is made from cartilage, and therefore no bones are left behind when they die. Without bones to study, it is very difficult to understand how the hammerhead has evolved.

Scientists have discovered that Hammerheads in their current form are relatively new to the ocean. Their origins have been a topic of dispute, with some believing the hammer took millions of years to evolve. The most common belief is that the Hammerhead Shark was once much larger, but has slowly decreased its size over the past 20 million years. Many fish have evolved to be smaller in order to reach sexual maturity faster. This allows them a better chance of progressing the species.

The Scalloped Hammerhead Shark: Out of the Blue!

What is the size, weight & colour of the Scalloped Hammerhead Shark?

Although it is sizeable, the Scalloped Hammerhead is smaller than its cousins. The Female can grow up to 4 meters in length weighing 150kgs, while the Male can grow up to 2 meters weighing 80kg. In comparison to other fish this is still large, and they are still just as effective at hunting as other Hammerheads. It is the size of the Scalloped Hammerhead that makes it easiest to catch for fishermen.

Also known as “The Bronze Hammerhead”. The Scalloped Hammerhead has a brown hue to its body compared to the greyer tones of its cousins. The fins on their pups are a much darker bronze hue, until they are able to swim in deeper waters and avoid sunlight. Like many fish in the ocean, they have adapted a white belly to avoid being seen from below.

What type of vision does the Scalloped Hammerhead Shark have, and what sounds do they make?

The difference in size between the Scalloped Hammerhead and its cousins means it has to watch out for some serious predators. Tiger Sharks are their top predator, alongside Killer Whales. They need to be alert while hunting down their own prey, not to become prey themselves. Scalloped Hammerheads have 360-degree sight, meaning they can view all angles apart from one blind spot, which is right in front of their mouth! This extraordinary vision comes in handy when hunting prey, and occasionally avoiding predators, and also aids when hunting in deep waters.

This shark, like many others, is not known to make any sounds, even their organs do not make any noise, which allows them to hunt in pure silence.

Are there any special or unique physical attributes?

The Cephalofoil is the mighty hammer that gives these creatures their name. The Scalloped Hammerhead has distinct divots lining their Cephalofoil. This acts as a rudder, as well as aiding electroreception. Hammerheads have a strong ability to hunt with magnetic fields underwater, which is a huge advantage alongside their superior vision.

In addition to hunting and evading predators, this facial fin allows the Scalloped Hammerhead to reach incredible speeds and buoyancy underwater. Hydrodynamics are essential to the success of this fish. Many scientists have observed these fish using their many fins to glide effortlessly on one side.

How fast is the Scalloped Hammerhead Shark?

Because of their high metabolic rate, the Scalloped Hammerhead has to move fast to catch as much prey as possible. They accomplish this with their streamlined body, propelled by hydrodynamic fins which allow them to move up to 40km/h.

How do they hunt, and what do they eat?

The Scalloped Hammerhead, much like its cousins, has a small mouth compared to the rest of its body. This means they must downsize their prey even further from other Hammerheads. Usually, the Scalloped Hammerhead will be seen preying on squids, Octopuses, shrimp, and if they’re lucky, juvenile stingrays. They lose teeth very often when attacking and pinning down fish and are luckily able to replenish these teeth every 24 hours. The Scalloped Hammerhead has more teeth than the great Hammerhead, about 48, or more.

Who are their natural enemies?

Scalloped Hammerheads have to work hard to evade larger sharks and killer whales. This is especially difficult because they hunt and travel in schools, which makes them easier targets than if they travelled alone. In the last 25 years, humans have become another natural enemy of Hammerheads. This specific shark is the most common prey to finning, where fishermen will cut off their fins and release them in the water to die. This mostly to make shark fin soup.

Where do they live?

This shark, much like its cousins, loves tropical coastlines. The most fascinating and unique behaviour in Scalloped Hammerheads is their prolific “schooling”. Dense schools of Scalloped Hammerheads occur in all tropical waters, especially near the Great Barrier Reef and Galapagos Islands. This happens for a variety of reasons, primarily for cleaning their bodies, but also for protection and hunting. These schools won’t form near the surface, instead, they will be found as deep as 400 meters.

What are their migration habits and routes?

Scalloped Hammerhead migration patterns vary. Many of these sharks don’t migrate at all, especially females. Females are much more likely to be found in sedentary schools during the day, about 500 strong. This is for strength in numbers, as females stick together to protect themselves from fighting males. They share the common trait with their cousins of solitary night hunting. Which is where their electromagnetic perception comes in handy.

Male Scalloped Hammerheads are likely to swim much deeper in pairs, migrating further along coastlines. Their homing senses guide them along with an inner map so they can always double back to schools for mating and cleaning.

How can they travel such long distances?

The large dorsal fin on the Hammerhead’s back allows it to make quick turns in and retain speed. The pectoral fins suspend the Scalloped Hammerhead in water, allowing it to glide with ease. All of their physical attributes have allowed these fish to maintain high speeds in open water.

All about Reproduction.

Scalloped Hammerheads are viviparous, meaning the mother nourishes her eggs from inside and they are born alive. After carrying them for 10 months, the female will find somewhere shallow to leave them. The female makes sure to do this in coastal waters where her pups will be far from predators. She will give birth to up to 40 pups, all-around 40-60cm, and 2kgs in weight. She will then leave them to fend for themselves. Many of these pups do not survive their first months.

The pups themselves will develop suntans while living in shallow water, which will fade as they transition into deeper water. This shark takes a long time to reach sexual maturity. With an average of 10 years for males, and 15 for females. Because they are slow to enter the reproductive cycle, a fall in numbers would take decades to replenish.

Life Span.

If these Sharks were not hunted, they would be able to live up to 35 years. However, most Hammerheads are captured when they are small, before they have reached sexual maturity.

Myths.

Many believe that cannibalism exists only on land and is not common in sea life. However, The Scalloped Hammerhead has been known to feed on its own kind when the opportunity presents itself. Cannibal fish are not common, but in dire circumstances it’s certainly an option for the Scalloped Hammerhead.

What threats does the Scalloped Hammerhead Shark face?

The greatest threat to The Scalloped Hammerhead is overfishing and legal practices of finning. While their own predators in the ocean contribute to their falling numbers, humans overfish and over fin (killing sharks for their fins). With 100 million sharks killed every year, the Hammerhead remains the most hunted, this makes humans their biggest threat.

Why are they endangered?

Sharks have been resilient to ecological change in the past. Yet having survived major extinction events over 400 million years, this does not guarantee they will continue to survive. The gradual depletion, along with a slow sexual maturation, makes it difficult for their populations to endure.

In the last 25 years, the populations of Hammerheads have depleted by 95%. They are the most commonly caught shark by far. Some parts of the world have seen greater depletion than others. In Africa this fish is considered critically endangered, due to unsustainable fishing practices and overfishing.

Endangered Ranking – CITES.

CITES voted in support of listing the Great, Smooth, and Scalloped Hammerhead as endangered in 2013. These 3 species have increased protection, only allowing sustainable trade to take place.

Currently, over 200 sharks occupy spots on the Red List of endangered species. According to the IUCN (International Union for Conservation of Nature) this is due to legalized finning practices. More progress needs to be made to ban finning practices worldwide, otherwise these numbers will continue to fall.

Why should you care?

As apex predators, The Scalloped Hammerhead is an essential part of the food chain. If the population of apex predators falls, then the ecosystem will collapse. Smaller fish will continue to deplete coral reefs, which will affect our oxygen supply. Ocean life and life on land are so delicately intertwined, that the removal of one species can add strain to our already vulnerable ecosystem. Humans rely on the benefits of healthy marine life just as much as fish do.

What can you do to help?

1. Ethical Consumption:  Shark fin soup is a delicacy in many parts of the world, Including the USA. Some medicines are also made from shark products, as well as their oils are used to wax boats. If you want to protect these important sea creatures, refuse to consume anything made from Sharks.

2. Spread the word! Talk to family members and friends about what they’re doing to help the cause. Inform people on more sustainable delicacies they can enjoy instead of Shark Fin Soup.

3. Get Involved: Lastly, spend time signing petitions and getting involved in online spaces. If you can, donate whatever you can to organizations like The Human Society International, which aims to protect sharks from finning.

If there is a public demand for change, then change will come. With everyone’s help we can create new standards for the ocean and all of its inhabitants! With safer oceans we will continue to see the Scalloped Hammerhead Shark populations stabilize.