Every year between the end of January and mid-May when the water is at its coldest and begins to warm up for summer, Blue Planet Aquarium has its annual Sand Tiger Shark mating season. During this time of year, the dynamics in the tank completely change, from what are usually slow moving and often sleeping sharks turn into fast moving Sharks who have only one thing on their mind.
In previous blogs I’ve mentioned how relaxed the Sharks are, but during this time the Sharks are at the complete opposite end of the scale, sometimes seeming oblivious to our presence, they can tend to almost “play chicken” with the divers, swimming very close, which can sometimes make us jump a little. Even with this change in behaviour however the animals are still quite easy to work with and we always respect their boundaries and rules as it is their home at the end of the day.
The changes in behaviour start around mid to late January with a huge reduction in appetite for all our Sand Tigers, they will go down to eating almost nothing throughout the mating season, we even have them spit food out after grabbing it.
The next sign usually starts with the males moving a lot faster and will duck and dive between the different levels in the tank, it can be chaotic one day and then almost nothing the next, on the opposite end the females will slow right down and tend to spend a large amount of time either on or near the bottom.
It is like this for about a month before the action really starts, the next sign is what’s known as “tracking”, this is where you will have the female of interest at the front with the alpha male close behind her, with the subordinate males trailing behind him. This happens for a couple of weeks until around March where the height of mating season starts, after a month or so of tracking and a little bit of bickering there will be an “alpha” male who will control mating in the tank. Alpha males will then protect the area where females are congregating and will then force less dominant males out by snapping their jaws at them, snapping tends to be enough to force males out, however seeing bite marks on the males is not uncommon.
When Sharks mate the males tend to bite the females around their pectoral fins or on their sides, this is done to help hold themselves in place during mating and to make it easier to mate by slowing the female down, females will often resist but will concede due to the extra weight, this could be the female testing the male’s fitness, but we honestly don’t know. The male sharks sex organs are known as Claspers, two small appendages that trail behind the Sharks pelvic fins and its these that transfer the Sperm to the female during mating, they have two so that they’re able to effectively mate no matter what side they approach the female on.
When males are finished and let go, they can sometimes leave teeth embedded in the females which will fall out after a few days and don’t affect the female long term, this does often result with toothless males during mating season, and even for a short time after it has finished, which our guests are often surprised to see gummy Sand Tigers in our exhibit. Along with having toothless males the females also become covered from nose to tail in love bites, and during rather amorous seasons the dive team will refer to the females as pin cushion Sharks due to how much they resemble pin cushions, never fear however because mere days after mating season has finished most, if not all, of the wounds on a female would have healed and results in very minor scarring or marks.
Females will mate with numerous males throughout a season, moving between different areas and mating with many alpha males who control those areas, in the case of Blue Planets main tank our males tend to gain and lose alpha status rather regularly, thus allowing them mating rights. Female Sand Tigers have two Uterus’s which can contain up to 5 pups each. After the mating season is over, females become pregnant in a rather remarkable way. Sand Tigers are known as oophagous which is where the developing embryos will feed on undeveloped eggs produced by the mother throughout her 9–12-month pregnancy.
But that’s not all, once an individual or individuals reach a certain size, they will actually turn on their sibling and begin to feed on them, this is called intrauterine cannibalism. This will continue until there is a single fully toothed pup in each uterus, however triplets have been recorded which believed to be two individuals from the same womb who were full sibling who teamed up, and one from the other womb.
This method of eating siblings is believed to be an adaptation by male Sand Tigers with whom who can father the most well-armed, active hunting embryos as described by a scientist called Damian Chapman.
Unfortunately, Blue Planet has never had a captive natural birth in our main exhibit now there could be many reasons as to why this is the case, and we have a few theories amongst the team but unfortunately, we just can’t say for certain what those are. The reasons as to why they aren’t breeding is something that been discussed for many years in aquariums across the globe as unfortunately captive breeding very limited with only a handful of recorded births worldwide.
Sand Tiger Sharks have one of the lowest reproductive rates of any Shark Species giving birth to only two pups every other year as the females take a rest year in between, on top of this Sand Tigers don’t become sexually mature until they’re between 6-7 if they’re a male, females will not become mature until they’re 9-10 this on top of the fact that the maximum lifespan recorded for a Sand Tiger in the wild is 15-17 years means that to be generous, a female may only give birth to a maximum of 16 pups throughout their lifetime. Now these natural adaptations have served them well throughout the last 450 million years but now they are a handicap.
Sand Tigers are unfortunately at threat, with some populations such as those in Europe, the Mediterranean and Eastern Australia classified as Critically Endangered. Sand Tiger Sharks were also the first Shark species to be put on the endangered species list and given full protection which was first done in Australia.
With all the odds stacking against them its now even more imperative that we learn more about these incredible animals and how to breed them effectively to create a captive population as a contingency plan in case things in the wild take a nosedive. Therefore, Zoos and Aquariums are important to the wild members of a species with housed members of the species, helping ensure their survival and as acting as ambassadors to the wild ancestors by educating our guests and the public for many years to come. Now rest assured although we haven’t yet been able to breed Sand Tiger Sharks in our main exhibit, we’re working hard to better understand and figure out how we can in the not-so-distant future.
For more about Blue Planet Aquarium visit their website by click here.
Dragons of the sea
Guest Blog by Staci-lee Sherwood
The most fascinating and unique characteristic of the Syngnathidae family is how it’s the male that gives birth. This fish family includes Seahorses, Pipefish and Seadragon. Having a head like a horse, Seahorses and Seadragons stand out as a fish species in the marine world. They are true rock stars of the ocean and a favorite among photographers. Their tiny size and elusiveness just add to their appeal.
Lesser known than their more famous cousins they are stars in their own right. These tiny dragons of the sea are larger in size with more color and intriguing patterns. Found only in southern Australian waters makes them rare. There are three recognized species, the Weedy, Leafy and newly described Ruby seadragon.
Elusive species are more alluring to scientists because of the chance to be the first to discover something new. Not much is known about their lives and researchers hope to shed light on these rainbow colored fish. Their diet consists of tiny mysid shrimp and other zooplankton. After mating the female deposits up to 300 eggs into the male’s brood patch who then fertilizes and carries them till birth. Despite their being much larger than Seahorses, which range in size from 1 – 6 inches, they produce about 1/3 of the eggs. Seadragons range in size from 13 – 18 inches
In 2006 the IUCN listed them as Near Threatened on the Red List. A lot has changed since then. As the Seahorse population continues to decline China might look more toward the Seadragon to fill the void.
One fascinating fact about this family of fish they lack teeth or stomachs. Instead they suck up food through their snout. Lacking a stomach means food goes in and out rather quickly. Seahorses will mate for life. During the courtship dance they curl their tails and change color. Following the mating ritual it’s the female that deposits up to 1,000 eggs in the male’s pouch. A handy survival skill, like the chameleon, they can change color to blend into their surroundings.
Diminutive in size they capture the imagination of young and old alike but are in serious danger of going extinct. Illegal harvesting by China for traditional medicine, used as decoration in key chains and pendants and polluted water have taken their toll. Without global bans on their exploitation and fierce enforcement the world could lose these horse looking fish. There are over 40 recognized species globally.
Many Floridians don’t know we have three species of seahorses, the Dwarf, Lined and Long Snouted. These are all listed as either Vulnerable or Threatened in US waters. One of the biggest threats in Florida is the heavily polluted water they live in. Seahorses live in shallow tropical waters where their habitat is coral reefs, seagrass beds and mangroves. Unfortunately in Florida the water quality is so poor most of the seagrass is dead while the bleaching of coral reefs has caused their decline. A bleak future awaits this species.
Globally all species are being pulled from the ocean so Florida populations are at risk of extinction. A favorite among divers, some local populations have fan clubs where divers will make special trips hoping to see them.
The White’s Seahorse, also known as the Sydney Seahorse, has a population decline over 90%. In 2018 they became the second seahorse species in the world to be listed on the IUCN Red List Status as endangered. Alarmed scientists took this opportunity to try to save them in a unique way. Research showed this species uses artificial reefs if natural ones are absent. David Harasti, Senior Research Scientist at Port Stephens Fisheries Institute, created the ‘Seahorse Hotels’ out of metal cages. Once placed underwater they soon attract a variety of marine life like Coral and Sponges. In a matter of weeks they’re covered and start attracting endangered Seahorses.
I spoke with Dr. Harasti about the use of these hotels for other species, especially those found in other parts of the world. Regarding their use Harasti said “the use of hotels may only be suitable for particular seahorse species. We know that they work really well for those species that like artificial habitats such as the White’s seahorse and Pot-belly seahorse in Australia and the Short-head seahorse found in Europe.”
Captive bred juvenile seahorses are released into hotels hoping they will breed and help recover their population. Surveys show adult seahorses have also taken to them. The project has only been around a few years so it’s too early to tell if the population will rebound. Illegal harvesting worldwide must stop and laws must be enforced. With such a steep decline of a species that gets little attention we need real conservation on a global scale now. Click here to learn more about these hotels and watch some amazing videos https://www.dpi.nsw.gov.au/fishing/species-protection/what-current/endangered-species2/whites-seahorse
In 2017 a photograph taken off the eastern coast of South Africa in Sodwana Bay by Savannah Nalu Olivier showed a new species barely the size of a fingernail. After viewing the photograph, pygmy seahorse expert Richard Smith realized this was a new discovery. This is the first pygmy seahorse discovered in the Indian Ocean. Most pygmy seahorses survive by camouflage among vegetation so what an amazing find to see something so microscopic. To read the 2020 study click here https://zookeys.pensoft.net/article/50924/
According to Seahorse Trust the biggest threat to survival is the taking of an estimated 150,000,000 every year, mostly by China, to be used in their traditional medicine. The use of Seahorses for asthma and impotence has no scientific basis and can be fixed with modern medicine. Another 1,000,000 are caught for captivity in personal aquariums. There are no accurate numbers for how many end up used in trinkets but it’s estimated 1,000,000 are lost. At this rate we will push this species toward extinction.
In the past twenty years there has been a global increase in the capture and selling for use in about 80 countries. Varying degrees of threats exist for different species and different regions. Somewhere between 50 -97% decline in their population makes for an urgent call to end their use whether for personal and medical reasons. The world must agree to a ban with enforcement or lose one of its most amazing creatures .
Help save our Seahorses and Seadragons with these do’s and don’ts:
- Don’t buy dried Seahorses, or trinkets that use them
- Don’t buy live Seahorses for aquariums
- Do use modern medicine which is effective and safe instead of Traditional Chinese Medicine
- Never pollute the water
- Support conservation efforts
- Spread the message
To learn how to help Seahorses https://www.theseahorsetrust.org/
To help conservation in Australia https://www.visitsealife.com/sydney/conservation/
Header Image: Tony Brown
For PADI divers, every week is Shark Week!
Some of our favorite places to have epic interactions with the stars of Shark Week – dive certification not always required!
We’ve been all around the world diving with sharks from the smallest shy shark to the giant whale shark. Here’s some of the best places in the world to swim, snorkel and dive with the iconic and most popular stars of Shark Week – including Whites, Bulls, Tigers, Great Hammerheads, and Mako Sharks – while shifting your perspective at the same time!
Great White Sharks – Guadalupe Island, Mexico
PADI Diving Certification required: None
Other Shark Species You’ll encounter: None (they don’t want to end up on the White Shark’s menu!)
Want to have the same experience people like PADI Diver Andy Casagrande film for Discovery’s Shark Week? Head to a remote archipelago off the coast of Baja.
Guadalupe Island is off the coast of Mexico and is absolutely epic for experiencing white sharks doing what they do best. This small volcanic island is located 150 miles off the west coast of Mexico and is home to approximately 170 great white sharks from July to November.
The water is crystal clear, topside conditions are usually great – and the action is incredible, and highly reliable. While we are dealing with wild animals that make their own itineraries, it isn’t unusual to see 20 – 30 different animals on a trip!
The island’s shores are havens for Guadalupe Fur Seals, Californian Sea Lions and Northern Elephant Seals. It also brings in incredible amounts of pelagic fish species like tuna. It’s a 24-hour diner filled with white sharks’ favorite food from late July through the end of each year.
Some of the biggest sharks in the world have been tagged in Guadalupe including “Deep Blue”. The action at the surface can be busy with the huge females hunting large elephant seals and from the in-water cages, it’s incredible to witness the social structures and the interaction between sharks.
Many operators serving Guadalupe Island offer the unique experience of liveaboard diving with great whites. While it may not be the easiest place to reach, thanks to the large population of migrating sharks and clarity of the water, this is a great choice for a great white shark encounter.
And you don’t need to be a certified diver! You’ll have surface supplied air and plenty of time in cages built for your – and the sharks’ safety.
Other White Shark Hotspots:
- Port Lincoln – Australia
- Gansbaii + False Bay, South Africa
- Farrallon Islands, California
- South Island, New Zealand
Tiger Sharks – “Tiger Beach”, Bahamas
PADI Diving Certification required: Open Water Diver or Freediver
Other Shark Species You’ll Encounter: lemon sharks, reef sharks, nurse sharks and the occasional great hammerhead
Named because of their unique stripes and impressive hunting style, tiger sharks can be found in tropical and sub-tropical regions around the globe. These beautiful marine animals can reach up to 5 meters/16 feet in length and can weigh up to 635 kg/1,400 lb.
Tiger sharks have gotten a bad reputation on Shark Week as being indiscriminate eaters (yes, it’s true a suit of armor and an unexploded grenade have been found in the stomachs of this species) – and dangerous sharks. However, swimming with one – whether snorkeling, freediving or diving is a life-changing experience. You’ll quickly realize that you are having an adventure of a lifetime as the fear melts away. And there is really no place on earth like this place off the coast of the Bahamas – that exists only below the surface.
About an hour by boat from the West End of Grand Bahama, Tiger Beach is famous and aptly named for its resident tiger sharks. Two to seventeen of these gorgeous animals reliably appear nearly every day of the year. Tiger Beach offers the chance to take part in some of the greatest shark diving in the world. You’ll get up-close encounters with not only tiger sharks but lemon sharks, the occasional hammerhead and plenty of whitetip reef sharks in the crystal-clear azure waters that only an aquarium can top in terms of visibility.
The best time to dive Tiger Beach is between October and January when the sharks use the area as a breeding ground. Shark Week has featured some of the residents being tagged or even giving birth – and hopefully you’ll even meet Emma, the world’s most famous Tiger Shark.
From Bimini or Grand Bahamas, you can head to the most spectacular tiger shark gatherings in the world by a day boat – or you can take a trip on a liveaboard departing from Southern Florida or the Bahamas. The easy surface conditions, 20-foot depth and gorgeous light make Tiger Beach accessible for freedivers and scuba divers alike.
Other Tiger Shark Hotspots:
Bull Sharks – Shark Reef, Fiji
PADI Diving Certification required: Advanced Open Water Diver
Other Shark Species You’ll Encounter: tiger sharks, gray reef sharks, nurse sharks, black tip reef sharks, silvertip sharks
Part of many different Shark Week episodes, bull sharks are well known sharks for many reasons – including a reputation for brutish behavior (which earns them their name) as well as the fact they are one of the most adaptable species of all sharks. They can survive in both salt and fresh water and can be found in most coastlines throughout the world. Although they’re portrayed as one of the more aggressive sharks on shark week, they are incredible creatures to see underwater and shouldn’t be missed. And there’s literally no better place to dive with bull sharks than Fiji – where you’ll find the biggest bull sharks in large numbers.
With the establishment of the Shark Reef Marine Reserve, Beqa Lagoon has become a premier shark diving area the world over. Bull sharks are the stars of the show here, but divers can encounter up to 7 other species as well. These include sickle lemons, gray reefs, nurse, blacktip reefs, whitetip reefs, silvertips and tiger sharks. With more than 20 dive sites in the lagoon, divers can fill a week or more with fantastic shark sightings. Although you will see sharks during any month of the year, July to September offer the best diving conditions in terms of visibility, water temperature and other large marine life.
As an added bonus, any diving done in the Shark Reef Marine Reserve finances shark research and compensates local fishermen for lost income due to the creation of no-take zones. It’s a win-win-win for sharks, divers and the local population!
A recent study in Fiji found that bull sharks form friendships with each other! Researchers studied data collected over 3,000 shark dives in Fiji’s Shark Reef Marine Reserve (SRMR), one of the world’s most sought-after diving destinations. SRMR is located in the Beqa Channel, off the southern coast of Viti Levu, and is a striking example of collaboration for conservation.
The shark is revered by local Fijians and legend has it that Dakuwaqa, the ancient shark god, provides protection for the people when at sea. So not only will you be exploring Fiji’s underwater world with your dive buddy, but you will likely encounter a pair of bull shark BFFs on your dive too!
Other Bull Shark Hotspots:
- Bimini, Bahamas
- Playa del Carmem, Mexico
- West Palm Beach and Jupiter,Florida
- Protea Banks, South Africa
Great Hammerhead Sharks – Bimini, Bahamas
PADI Diving Certification required: Open Water Diver or Freediver
Other Shark Species You’ll Encounter: bull sharks, lemon sharks, reef sharks, nurse sharks and don’t forget the shark’s close cousin… the eagle ray
Bahamas makes it on our list twice thanks to the incredible conditions underwater (there’s actually a color named Bimini Blue), and the fact the Bahamas plays hosts to some of the most spectacular mega-fauna in the world – including the Great Hammerhead Shark.
There’s no mystery as to how the hammerhead shark got its name! That massive hammer – known as a cephalfoil – makes them one of the most distinctive animals on the planet. And that hammer isn’t just for show… It gives this shark superpowers which means the great hammerheads have seven finely attuned senses plus 360-degree vision (without turning their head!) to be able to avoid divers. Seeing a great hammerhead is rare as they tend to be quite skittish underwater, so finding a place you can reliably experience them is a rarity.
Every winter from December to March, great hammerhead Sharks gather around Bimini in large numbers. Naturally shy and reserved, these huge sharks with their odd faces become curious in this location, closely approaching divers. Shark diving is closely controlled due to the area’s marine park status. Although Bimini Island is a part of the Bahamas, it is located just 50 miles from Miami in the United States, making it possible to visit by boat in just three hours from the American city.
The waters of Bimini are warm, clear and typically protected. The shark dives occur in less than 20 feet of water allowing divers and freedivers to enjoy incredible encounters.
Plan a trip to Bimini to see the “hammers” and you’ll likely catch up with bull sharks, friendly dolphin pods, and graceful schools of eagle rays. You’ll feel like you stepped back in time to an island still not heavily commercially developed and traversed by golf carts. Bimini can be explored by divers and snorkelers alike – and is absolutely stunning above and below the surface. Head to nearby Honeymoon Beach to swim with the local group of rays as well – after all, rays are really just flat sharks!
Other Great Hammerhead Hotspots:
- Southern Florida, USA
- Rangiroa, French Polynesia
- Solomon Islands
Shortfin Mako Sharks – Rhode Island, USA
PADI Diving Certification required: None
Other Shark Species You’ll Encounter: blue sharks
Mako sharks get nearly as much airtime on Shark Week as white sharks, thanks to their incredible biology, although the fact they are in the same shark family as whites (mackerel) probably doesn’t hurt!
Shortfin mako sharks are sometimes described as miniature great whites on amphetamines. These toothy sharks look like a shrunken-down version of the ocean’s top predators, but they act totally differently. While great white sharks slice slow, graceful circles around a diver, watching with an inquisitive eye, makos are twitchy sharks, hopped up on adrenaline, that speed past you.
Thought to be the fastest sharks in the ocean, makos have an estimated top speed burst of about 45 mph. They can achieve these speeds thanks, in part, to their ability to thermoregulate – meaning they can warm their body temperatures. Incredible acrobats, like great whites, makos are known to jump out of the water, sometimes up to 20 feet in the air, using their perfectly shaped fins as wings and rudders.
Equally impressive, they have the largest brain to body mass of any study shark as well. So they have it all – beauty, brains and braun.
Makos are pelagic sharks that live throughout the world’s oceans, but there are only a handful of places where you can have reliable encounters with these incredible creatures. Our favorite, most reliable place? Rhode Island. Plus, you don’t even have to be a diver!
Most people don’t think of Rhode Island as a shark-diving hot spot, but during the summer months, when the Gulf Stream moves close to shore, this stretch of New England coastline becomes a haven for makos and other sharks, as game fish move closer to shore. You can even join PADI divers, PADI AWARE supporters and Shark Week celebrities Joe and Lauren Romiero as they film and study the local mako population on their dive charter.
Even if you miss the stars, the equally charismatic blue sharks steal the show.
Other Mako Hotspots:
- Baja Sur, Mexico
- Cape Point, South Africa
- San Diego, California
Header Image Credit: Andy Casagrande @ABC4EXPLORE
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