CREATURE FEATURE: MEGAMOUTH SHARK

This month we have guest writer - Jodie Moore. 33-year-old Jodie recently graduated with a BSc in Animal Biology and Wildlife Conservation. She's soon to be commencing an MSc in Marine Conservation and is an avid volunteer in the field. She is an ocean ambassador with the UNA Climate & Oceans, an observational data gatherer with SeaSearch and a trainee Mammal Medic with British Divers Marine Life Rescue. She's always had a deep love and passion for the ocean, but her particular interest in sharks stems from the film Jaws. 

A rare and mysterious species, the Megamouth Shark Megachasma pelagios was first sighted when one had become 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 coastal to open ocean habitats (epipelagic to bathypelagic), and is a filter feeder, like both Whale and Basking Sharks (Oceana, 2023).

Upon its 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 of Threatened Species, with the most recent assessment of species health being in 2018 (IUCN Red List, 2023). The Megamouth Shark can be found in countries Australia, Sri Lanka, Vietnam, South Africa, and China, with the population number of sharks currently unknown due to rare sightings, and a lack of research around them (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 or captured a handful of times The smallest of the three species of filter-feeding sharks, this shark derived its name from its remarkably large, circular mouth (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 fertilisation, giving birth to a small number of live young (Oceana, 2023). The adult shark does not connect to their live young through a placenta, instead the mother provides an unfertilised egg during gestation (Oceana, 2023). Once born, the megamouth shark immediately becomes a filter feeder (Oceana, 2023). There is a huge lack in species behavioural ecology and richness, and so further research is needed in order to better understand and 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

Illustration - © Marc Dando

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Author: Conor John

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