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Creature Feature: Basking Shark

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In this series, the Shark Trust will be sharing amazing facts about different species of sharks and what you can do to help protect them.

This month our Creature Feature is from guest writer – Yolanda Evans. 17-year old Yolanda has been passionate about sharks all her life. And this month she explores the world of the Basking Shark.

Slowly gliding through the water is the 12 metre Basking Shark. The second largest shark in the world, but also the biggest in British waters, these sharks are immediately identifiable from their large agape mouths and their brown-grey colouration. In fact, they are so big that their species name ‘maximus’ means great, for their great size.

Basking Sharks’ capacious mouths can be up to 90cm wide but despite their size, they eat some of the smallest creatures, zooplankton. Their food is separated from the water by their gill rakers, these are long keratinous bristle structures that are in each gill. Even though they eat zooplankton, Basking Sharks still have teeth. There can be up to 200 in both their upper and lower jaws. However, unlike their cousins the infamous White shark, their teeth are only 5mm long!

Very little is known about Basking Shark pups. In fact, only one female has ever been recorded carrying an embryo! It is widely believed that Basking Sharks are ovoviviparous, meaning that eggs inside the female hatch before she gives birth. Basking Shark pups are born with almost a hooked snout. This hooked snout is thought to help the pup to feed while still in the mother; the pup will rapidly outgrow this hooked snout after about a year.

They swim close to the surface of the water causing their dorsal fin to break the top. Basking Sharks can often congregate in shivers (a group of sharks) of over 100 sharks. They display a number of courtship behaviours including snout-to-tail lines, parallel swimming, and even breaching, this is when the shark jumps out of the water!

Their common name also comes from where they swim, as it is thought these mighty sharks like to bask in the warmth of the sun. In fact, like many sharks and ourselves, Basking Sharks can actually get a tan from the sun! Their tan makes them go a darker brown.

They have a global distribution and are a common visitor to British waters! Basking Sharks are a migratory species. They can be found in the UK from May to October on the west coast of the UK and then undergo trans-Atlantic migrations along the continental shelf following the zooplankton. If you do see a Basking Shark in the wild always remember the Basking shark code of conduct.

The Basking shark is currently recognised as endangered and is on the IUCN red list. It was until 1994 that Basking sharks were hunted for their liver oil in the UK. The oil was used for streetlamps and cosmetics. Shark liver oil is made of a substance called squalene which is still used today in many products like sun creams and makeup.

REPORTING YOUR SIGHTINGS – You can report your sightings of Basking Shark wherever you are in the world, to our Basking Shark Project!

SCIENTIFIC NAME: Cetorhinus maximus

FAMILY:  Cetorhinidae

MAXIMUM SIZE: 12m

DIET: Zooplankton

DISTRIBUTION: Worldwide

HABITAT: Coastal and Pelagic waters

CONSERVATION STATUS:


Banner Image – © Martin Prochazkacz via Shutterstock

In-Text Images – © Frogfish Photography


For more amazing facts about sharks and what you can do to help the Shark Trust protect them visit the Shark Trust website by clicking here.

The Shark Trust is the leading UK-based shark conservation charity. The team works globally to safeguard the future of sharks, and their close cousins, the skates and rays. Engaging with a global network of scientists, policymakers, conservation professionals, businesses and supporters, to further shark conservation. Established in 1997 to provide a voice for UK sharks, the Shark Trust has an ever-growing number of passionate supporters. And together we're creating positive change for sharks around the world. Want to join us and help protect sharks around the world? Click here! www.sharktrust.org

Marine Life & Conservation Blogs

Creature Feature: Goblin Shark

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In this series, the Shark Trust will be sharing amazing facts about different species of sharks and what you can do to help protect them.

Written by guest contributor – Yolanda Evans.

Mysteriously slithering around the dark mesopelagic of the western Pacific, the glorious Goblin shark swims in search for their next meal. This illusive shark is one of the most unique-looking sharks to ever exist, having a long snout called a rostrum and protrusible jaws, hailing them their common name, Goblin. Their rostrum is covered with small pores called the ampullae of Lorenzini, jelly-filled pores in the snouts of many sharks that are able to pick up changes in the electro-magnetic field, for example the muscle contractions of nearby fish. However, these pores can only detect movement only a few inches in front of the shark!

In addition to their rostrum, these sharks poses and amazing ability to protrude their jaws out or their cartilaginous skull by something called slingshot feeding. This is when the jaws are shot forward, extending 8.6-9.4% of the Goblin sharks total body length. However, this fast jaw action also creates a powerful suction-known as a pharyngeal suction-forcing their prey deeper into their mouths.

While many sharks range from greys to blues to browns, this stupendous shark can be a very pale pink! However, this unusual colour is not from a pigment in their skin, but from the thinness of their skin! Their skin has such a great transparency that the oxygenated blood that flows in their capillaries-tiny blood vessels-causes what would be their grey skin, to become pink. This amazing ability might actually been an adaptation for the shark, they live 270m-1300 m deep, red light wavelengths cannot be seen, making the spectacular shark near invisible to both prey and predators!

Their scientific name, Mitsukurina owstoni, comes from the British naturalist Alan Owston who is credited with discovering the shark, and from Kakichi Mitsuriki, the Japanese scientist who identified and described the shark. While the English common name is only from their long rostrum, the direst translation into Japanese is Tengu-zame, base of the Tengu, a Japanese mythological half-man-half-bird who had red skin and a long nose, a comparison more fitting.

Despite their somewhat intimidating appearance, the Goblin shark is not an aggressive species, predating on mainly small bony fish, crustaceans, and cephalopods. Long slender teeth that protrude out from their jaws, appearing almost like blades, are perfect for clutching onto their prey. Nonetheless, the most threat they create towards humans is disrupting our internet as they are known to bite down onto submarine cables!

Like many other shark species, Goblin sharks main threat is by-catch from deep-sea longlining and deep-sea trawling. They are listed by the IUCN as least concern. Unfortunately, being relatively understudied, this may be incorrect as there is a very minimal amount of knowledge about the lives of these sharks. Leaving the question: what else is there to know about the truly incredible Goblin shark?

SCIENTIFIC NAME: Mitsukurina owstoni

FAMILY: Mitsukurinidae

MAXIMUM SIZE: Up to 3.8 meters (12.5 feet) in length

DIET: Feeds primarily on deep-sea fish, but also crustaceans and cephalopods

DISTRIBUTION: Goblin Sharks have a wide but patchy distribution, found in deep waters of the Atlantic, Indian, and Pacific Oceans.

HABITAT: Primarily found in the deep sea, typically between 200 and 1,200 meters (656 and 3,937 feet) in depth. They are occasionally seen at shallower depths, but are typically associated with steep slopes and canyons on the continental shelf and slope.

CONSERVATION STATUS:

Due to their deep-sea habitat and elusive nature, they are rarely encountered and little is known about their population trends. However, they are sometimes caught as bycatch in deepwater fisheries, and there is concern over the potential impacts of deep-sea mining activities on their habitat.


Images – www.fishesofaustralia.net.au/home/species/3254 | Wikimedia Commons

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Marine Life & Conservation Blogs

Creature Feature – Megamouth Shark

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A rare and mysterious species, the Megamouth Shark Megachasma pelagios was first sighted when one had gotten entangled in a sea anchor (Oceana, 2023), and hauled up by fishermen on-board a navy ship in 1976 (Black, 2014). The Megamouth Shark is distributed worldwide in tropical to temperate latitudes, can be found in costal to open ocean (epipelagic to bathypelagic), and is a filter feeder, like that of the Whale, and Basking Shark (Oceana, 2023).

Upon its first discovery, this genus of shark generated its own taxonomy, Order Lamniformes (mackerel sharks), and belongs to the family Megachasmidae (megamouth sharks) (Oceana, 2023). Currently this shark is listed as least concern on the IUCN Red List, with the most recent assessment of species health being in 2018 (IUCN Red List, 2023). The Megamouth Shark can be found resident in countries such as Australia, Sri Lanka, Vietnam, South Africa, and China, with the current population number of sharks being unknown due to their rare sightings, and lack of research (IUCN Red List, 2023).

A large species of shark, reaching weights of up to 2700 pounds (1215kg), and approximately 16 feet in length (5m), this species has only been observed within the wild a few times, with less than 60 individual sharks having been known by scientists to of ever been captured or observed (Oceana, 2023). The smallest of the three species of filter-feeding sharks, this shark derived its name from its remarkably large, circular mouth (Oceana, 2023). From what little research has been carried out on the species, from the rare few sightings these sharks have been observed residing near to the surface, in depths of up to 15,000 feet (4600m) (Oceana, 2023).

It is believed that Megamouth sharks only come near to the surface at night, spending the majority of their lives in the dark (Oceana, 2023). They are filter feeders that swim through the ocean with their mouths open capturing food resources, such as plankton (Oceana, 2023). The inside of their mouths contain light producing organs, believed to be used for attracting pelagic crustaceans and other prey (Oceana, 2023).

With commercial fisheries pushing to deeper depths to discover new species to market as food, more and more large deep sea creatures are being discovered (Oceana, 2023). Like other species of shark, megamouths mate via internal fertilization, giving birth to a small number of live young (Oceana, 2023). The adult shark does not connect to their live young through a placenta, and instead the mother provides an unfertilized egg during gestation (Oceana, 2023). Once born, the megamouth shark immediately becomes a filter feeder (Oceana, 2023). There is a huge lack in species behavioral ecology, and richness, and so electronic tagging studies and further research is needed in order to better understand, and to conserve this species (Watanabe & Papastamatiou, 2019).

SCIENTIFIC NAME: Megachasma pelagios

FAMILY: Megachasmidae

MAXIMUM SIZE: Up to 5.5 meters (18 feet) in length

DIET: Filter feeds for plankton, but also consumes deep water fish

DISTRIBUTION: Widespread distribution in tropical and temperate waters worldwide

HABITAT: Ocean-going. Surface to deep waters – 1,000m.

CONSERVATION STATUS:

Due to its elusive nature and rare sightings, little is known about its population size or trends. It is occasionally caught as bycatch in fishing gear, but there are no known directed fisheries for this species.


Banner image – Wikimedia Commons | GordonMakryllos

References:

This month’s Creature Feature has a guest writer – Jodie Moore

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