Shark Facts

Shark Cage Diving Season South Africa

You can go shark cage diving in South Africa throughout the year however the water visibility is best (clearest) between March and September, from autumn to spring.

Great White Shark Cage Diving Australia

The season runs all year round with best water visibility conditions in the summer months of November to January. Shark numbers are said to be highest in May.

Great White Shark Diving Guadalupe

The season runs from July through to December, with some of the highest sighting frequency and best diving conditions in the world, with a range of 20-50m of visibility. Wow!

Great White Diving in Cage Farallon Islands, California

Great White sharks arrive along the California coast in the middle of the summer and hunt until around January, cage diving with sharks trips are generally only offered in peak season from about September-November.

Most sharks are cold-blooded. The Great white shark and the Mako are partially warm-blooded (they are endotherms). These sharks can raise their temperature above the ambient temperature of the water; they need to have occasional short bursts of speed in hunting and thus need more muscles which are more efficient.

White Sharks and other lamnidae are also able to elevate the temperature in their stomach up to 17Β°C above the ambient water temperatures.

A cold-blooded animal has a body temperature that varies along with the outdoor temperature.

Like other fish, sharks “breathe” through their gills, which are respiratory organs akin to our lungs. As water passes over the gill’s membranes, tiny blood vessels extract oxygen from the water. Other sharks use ram ventilation; that is, they ventilate their gills by swimming very fast with their mouths open.

Sharks don’t have lungs, but they do have to breathe oxygen to survive. Instead of breathing air, though, sharks get oxygen from the water that surrounds them. The concentration of oxygen in water is much lower than in air, so animals like sharks have developed ways to harvest as much oxygen as they can.

Oxygen-rich water flows through the gills during movement allowing the shark to breathe. Some sharks such as the nurse sharks.

Nurse sharks do not need to swim in order to pump water through their gills. They what is called Buccal pumping and this works by using oral muscles to literally suck water in through their mouth and then move it over its gills.

Sharks do not sleep like humans do, but instead have active and restful periods

Like other fish, sharks “breathe” through their gills, which are respiratory organs akin to our lungs. As water passes over the gill’s membranes, tiny blood vessels extract oxygen from the water. Carbon dioxide waste also passes from the shark’s blood and out of its body through the gill tissue

Sharks can have up to seven external gill openings, but most species have five. Gill arches are considered part of the skeleton; they hold the gills in place. The arches support one or two rows of gill filaments.

Some sharks that live in shallow reef areas, have adapted to live up to 12 hours or so outside of water (should the reef dry up). However, most large shark species can only go short periods of time outside of the water, including the Great white sharks.

Epaulette sharks can survive for hours with little oxygen, and can clamber over land to reach the nearest suitable area of water. Most sharks however, are not adapted for this.

Shark do not breathe oxygen from the air with lungs like we and dolphins do, so for this reason sharks do not surface to breathe.

Ragged tooth/ sand tigers/ grey nurse sharks will occasionally gulp air on the surface which is believed to help aid them in their buoyancy.

Some sharks must swim constantly in order to keep oxygen-rich water flowing over their gills, but others are able to pass water through their respiratory system by a pumping motion of their pharynx. This allows them to rest on the sea floor and still breathe.

Like other fish, sharks “breathe” through their gills, which are respiratory organs functioning like our lungs. As water passes over the gill’s membranes, tiny blood vessels extract oxygen from the water.

Most species of shark need to remain in constant motion to keep water flowing over their gills in order to extract oxygen, or else they’ll essentially suffocate.

But like all animals, sharks still need to sleep. So how do they rest when they need to swim in order to breathe?

While some species of sharks do need to swim constantly, this is not true for all sharks.

Of the 500 or so shark species found in the world’s oceans, only about two dozen are known as β€œobligate ram ventilators”,. This means they need to constantly force water across their gills in order to breathe, typically by swimming at speed or finding a fast moving current to remain in. These sharks are among the fastest, most formidable predators of the sea.

Β 

Some shark species, such as the nurse shark, can breathe while stationary. They do this by drawing water through their mouths (or through an opening behind each eye known as a spiracle) which is then passed it over their gills and oxygen is extracted.

These so-called β€œbuccal pumpers” (β€œbuccal” refers to the cheek or mouth) don’t need to constantly swim to stay alive, and can often be found resting on the seafloor. Some shark species practice both methods of breathing, allowing them greater flexibility in getting rest and finding food.

Interestingly, very few shark species have ever been witnessed sleeping, and many scientific mysteries still exist around shark shuteye. Previous research has suggested that a shark’s swimming motion is actually coordinated by its spinal cord, not its brain. This may be how they manage to fall asleep, or rest, while continuing to move. Basically their brain naps while their bodies still sway, propelling them forward.

Here’s a question that many shark fans ask themselves… How do sharks sleep? Well, they don’t sleep in the way we humans think of sleep, or experience sleep.

In fact, some sharks can’t sleep at all, and the ones that do, never close their eyes.

Some shark species do, however, cycle through alternating periods of alert wakefulness and profound rest that is similar to sleep. We are pretty certain that sharks do not dream the way humans and some other animals do.

Recent studies show that it is the spinal cord, and not the brain, that causes sharks to swim. For this reason, it is now believed that some always-moving sharks may experience rest periods wherein their brains are less active.

Generally, sharks that spend time at the bottom of deep and shallow water are able to cease moving and remain at rest, or near-sleep, on a coral reef or sandy sea bottom. While wide awake and in motion, bottom dwelling sharks ventilate the same way as pelagic sharks. When they require deep rest, they sink or swim to the bottom where they sleep while breathing via the spiracles behind their eyes.

Shark skin is not made up of traditional fish scales. Everyone knows that sharks are the top predators in the ecosystem and as such they are armed with a mouthful of teeth. This enables them to hunt and eat their prey. But, it’s not just their mouths that are toothy: Sharks, skates, rays, and some other fish have tiny teeth-like scales that cover their bodies and function as their skin.

These tiny teeth that form sharks’ skin are called dermal denticles or placoid scales and are made of a matrix of microscopic, hard, tooth-like structures. These give the skin very tough armour with a texture like sandpaper.

These denticles are super smooth, just like velvet, if you were to touch it going in one direction but very rough to the point of being able to cut you if you touched it going in the other direction. They also help the shark to swim faster and more quietly by pushing the water down, helping it to move more efficiently by decreasing drag and turbulence. This is why Olympian swimsuit designers have based technology on shark skin when creating a fabric that mimics the exact proportion of the shark’s denticles, hugely improving a swimmer’s speed.

Some zoologists even suggest that early ancestors of sharks developed shark skin before developing teeth, and that shark skin is the basis of teeth formation for all modern day animals.

httpss://youtu.be/jHGTZmKWEnU

Shark skin is made of a matrix of tiny, hard, tooth-like structures called dermal denticles or placoid scales.

These structures are shaped like curved, grooved teeth and make the skin very tough armour with a texture like sandpaper.

Tiger Shark Skin

The Tiger shark, scientific name Galeocerdo Cuvier, has skin that can range from blue to light green, with a white or light yellow underbelly. Dark spots and stripes are most visible in young sharks. The spots and stripes fade as the shark matures. Tiger sharks are named for the dark, vertical stripes found mainly on juveniles. As these sharks mature, the lines begin to fade and almost disappear.

Sharks are known for their jaws lined with razor-sharp teeth, but their skin also contributes to their reputation of being a top predator.

Their skin is covered with tooth-like scales structures known as denticles that make shark skin rough like sandpaper.

Yes, sharks do have scales and they are super interesting, here are some facts!

  1. You could pet a shark from their head to tail without hurting your hand at all. If you go the other way, you would be missing half of your hand as their scales are like a cheese grater, arranged so that they go one way.
  2. Their scales help them swim, they bristle like a brush would and as they swim down, it helps them swim more efficiently by pushing out.
  3. They have the same structure as a tooth without the outer enamel layer, dentine, and a central pulp cavity.
  4. As sharks grow, their scales don’t increase in size. Instead the shark grows more scalesΒ 

Depending on the species of shark, the process of reproduction could be sexual or asexual. With sexual reproduction there is the mating of a male and female shark that takes place. The male is able to deposit sperm into the female which will fertilize the eggs. Asexual reproduction refers to the females being able to create and sustain a shark pup without a male shark and without ever having mated. This has only ever been observed in the cases of sharks in captivity, but may well occur in the wild where there is a severe shortage of male sharks. It is an incredible adaption to ensure species survival.

Most shark species have NEVER been observed mating in the wild. It’s probably a pretty rare event in their lives (females of many shark species only reproduce once every two to three years, though they likely mate several times per mating season).

Depending on the species, sharks are either born from eggs laid in egg cases or are born alive. About 100 shark species lay eggs in egg cases. This is called oviparous sharks or egg laying sharks, including bullhead sharks, such as the Port Jackson and Zebra sharks, and some carpet and cat sharks. Unlike bony fish, which lay eggs that are fertilized outside the female’s body, the male shark fertilizes the eggs within the female’s body, and the eggs are then deposited in an egg case, which is expelled into the sea. Here they attach to algae or coral. The egg case is soft and flexible at first, but hardens in the water. The young develop inside the eggs, hatch, and leave behind an empty egg case, which often floats onto shore. An opening in the empty egg case is evidence the sharks hatched and dispersed.

Sharks that are not born from eggs in egg cases are born alive. There are two ways in which live birth reproduction is accomplished among sharks. The most common way is called ovoviviparity. Ovoviviparous sharks have eggs that develop within the mother’s body. The eggs are fertilized internally and the developing sharks are nourished by the egg yolks. The young hatch within the oviduct and continue to receive nourishment from the remainder of the egg yolk, still attached to their body, as well as from fluids secreted into the oviduct. Some species of shark are cannibalistic, feeding on other eggs and embryos within the oviduct. Only a small number of these pups survive until birth. The young are then born live, and are fully functional. Most sharks are ovoviviparous, including Great white sharks, Mako sharks, nurse sharks, tiger sharks, and many others.

The other live birth method is called viviparity. The eggs of viviparous sharks are fertilized within the mother’s body, and the young are nourished by a placenta. The placenta is formed when the yolk sack comes into contact with the uterine wall. The placenta transfers nutrients to the young using the blood streams of the mother and babies, similar to the way mammal babies are nourished. The uterine wall also secretes fluids that are absorbed into the yolk stalk to nourish the developing pup. The young are then born live and fully developed. Viviparous sharks include bull sharks, whitetip reef sharks, lemon sharks, blue sharks and hammerheads, among others.

It is important to understand that sharks are predators. This means they must catch and kill their prey in order to eat and thus to survive. Unfortunately it is inevitable that sharks come into contact with humans, and just like humans, they can make mistakes.

The Great white shark has the highest recorded unprovoked attacks on humans. This is followed by the tiger shark, then bull sharks and thereafter the blacktip shark.

Great white sharks are at around 1.3 m (3.9 feet) when born, and grow about 25 cm (9.8 in) each year for the first few years of their live, slowing down thereafter.

Females grow faster than males.

Shark Skin

Shark skin is not made up of traditional fish scales. Everyone is knows that sharks are the top predators in the ecosystem and as such they are armed with a mouthful of teeth. This enables them to hunt and eat their prey. But, it’s not just their mouths that are toothy: Sharks, skates, rays, and some other fish have tiny teeth-like scales that cover their bodies and function as their skin.

These tiny teeth that form sharks’ skin are called dermal denticles or placoid scales and are made of a matrix of microscopic, hard, tooth-like structures. These give the skin very tough armour with a texture like sandpaper.

These denticles are super smooth, just like velvet, if you were to touch it going in one direction but very rough to the point of being able to cut you if you touched it going in the other direction. They also help the shark to swim faster and more quietly by pushing the water down, helping it to move more efficiently by decreasing drag and turbulence. This is why Olympian swimsuit designers have based technology on shark skin when creating a fabric that mimics the exact proportion of the shark’s denticles, hugely improving a swimmer’s speed.

Some zoologists even suggest that early ancestors of sharks developed shark skin before developing teeth, and that shark skin is the basis of teeth formation for all modern day animals.

httpss://youtu.be/jHGTZmKWEnU

Shark skin is made of a matrix of tiny, hard, tooth-like structures called dermal denticles or placoid scales.

These structures are shaped like curved, grooved teeth and make the skin very tough armour with a texture like sandpaper.

Tiger Shark Skin

The Tiger shark, scientific name Galeocerdo Cuvier, has skin that can range from blue to light green, with a white or light yellow underbelly. Dark spots and stripes are most visible in young sharks. The spots and stripes fade as the shark matures. Tiger sharks are named for the dark, vertical stripes found mainly on juveniles. As these sharks mature, the lines begin to fade and almost disappear.

Sharks are known for their jaws lined with razor-sharp teeth, but their skin also contributes to their reputation of being a top predator.

Their skin is covered with tooth-like scales structures known as denticles that make shark skin rough like sandpaper.

Yes, sharks do have scales and they are super interesting, here are some facts!

  1. You could pet a shark from their head to tail without hurting your hand at all. If you go the other way, you would be missing half of your hand as their scales are like a cheese grater, arranged so that they go one way.
  2. Their scales help them swim, they bristle like a brush would and as they swim down, it helps them swim more efficiently by pushing out.
  3. They have the same structure as a tooth without the outer enamel layer, dentine, and a central pulp cavity.
  4. As sharks grow, their scales don’t increase in size. Instead the shark grows more scalesΒ 

Depending on the species of shark, the process of reproduction could be sexual or asexual. With sexual reproduction there is the mating of a male and female shark that takes place. The male is able to deposit sperm into the female which will fertilize the eggs. Asexual reproduction refers to the females being able to create and sustain a shark pup without a male shark and without ever having mated. This has only ever been observed in the cases of sharks in captivity, but may well occur in the wild where there is a severe shortage of male sharks. It is an incredible adaption to ensure species survival.

Most shark species have NEVER been observed mating in the wild. It’s probably a pretty rare event in their lives (females of many shark species only reproduce once every two to three years, though they likely mate several times per mating season).

Depending on the species, sharks are either born from eggs laid in egg cases or are born alive. About 100 shark species lay eggs in egg cases. This is called oviparous sharks or egg laying sharks, including bullhead sharks, such as the Port Jackson and Zebra sharks, and some carpet and cat sharks. Unlike bony fish, which lay eggs that are fertilized outside the female’s body, the male shark fertilizes the eggs within the female’s body, and the eggs are then deposited in an egg case, which is expelled into the sea. Here they attach to algae or coral. The egg case is soft and flexible at first, but hardens in the water. The young develop inside the eggs, hatch, and leave behind an empty egg case, which often floats onto shore. An opening in the empty egg case is evidence the sharks hatched and dispersed.

Sharks that are not born from eggs in egg cases are born alive. There are two ways in which live birth reproduction is accomplished among sharks. The most common way is called ovoviviparity. Ovoviviparous sharks have eggs that develop within the mother’s body. The eggs are fertilized internally and the developing sharks are nourished by the egg yolks. The young hatch within the oviduct and continue to receive nourishment from the remainder of the egg yolk, still attached to their body, as well as from fluids secreted into the oviduct. Some species of shark are cannibalistic, feeding on other eggs and embryos within the oviduct. Only a small number of these pups survive until birth. The young are then born live, and are fully functional. Most sharks are ovoviviparous, including Great white sharks, Mako sharks, nurse sharks, tiger sharks, and many others.

The other live birth method is called viviparity. The eggs of viviparous sharks are fertilized within the mother’s body, and the young are nourished by a placenta. The placenta is formed when the yolk sack comes into contact with the uterine wall. The placenta transfers nutrients to the young using the blood streams of the mother and babies, similar to the way mammal babies are nourished. The uterine wall also secretes fluids that are absorbed into the yolk stalk to nourish the developing pup. The young are then born live and fully developed. Viviparous sharks include bull sharks, whitetip reef sharks, lemon sharks, blue sharks and hammerheads, among others.

It is important to understand that sharks are predators. This means they must catch and kill their prey in order to eat and thus to survive. Unfortunately it is inevitable that sharks come into contact with humans, and just like humans, they can make mistakes.

The Great white shark has the highest recorded unprovoked attacks on humans. This is followed by the tiger shark, then bull sharks and thereafter the blacktip shark.

Great white sharks are at around 1.3 m (3.9 feet) when born, and grow about 25 cm (9.8 in) each year for the first few years of their live, slowing down thereafter.

Females grow faster than males.

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TRIP STATUS

TOMORROW

Tuesday
27 June 2023

Next trip 28 June
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*Trip status updated daily at 16h00 SAST