Megamouth shark

Aquatic scientific names in the news …

Megamouth shark

15th April – a Megamouth shark has been reported caught in a fishing net about three miles from the Owase Port in Mie Prefecture, Japan.

megamouthPhoto showing the size of the mouth.

An extremely rare species of deepwater shark, it is the smallest of the three extant planktivorous sharks alongside the whale shark and basking shark, growing to a length of around 5.5 metres (male), 7.0 metres (female).

megamouth2Images: Sunrise/Channel 7

It is a filter-feeder, it feeds by swimming slowly (1.5–2.1 km/h) with its enormous mouth wide open, filtering the water for plankton, during the day at a depth of around 120–160 m, but as the sun sets rising to spend the night at depths of between 12 and 25 m, demonstrating a pattern of vertical migration seen in many marine animals as they track the movement of plankton in the water column.

The first Megamouth shark to be seen was discovered in 1976 off the coast of Kāneʻohe, Hawaiʻi, when it became entangled in the sea anchor of United States Navy ship, it was not until 1983 that it was identified as a new species and officially described.

Megamouth sharks remain rare, up until 2015 only around 60 sightings had been recorded although one source now suggests 103 sightings to date – see http://sharkmans-world.eu/mega.html

Megachasma pelagios  Taylor, Compagno & Struhsaker, 1983 – Megamouth shark

Etymology.

Megachasma – Greek, Megamegas (μεγας), large, great; chasma, xasma (χασμα), yawning hole, open mouth – alluding to the size of the mouth.

pelagios – Greek, (πελαγιος), of the open sea.

Ref. Megamouth – a new species, genus, and family of lamnoid shark (Megachasma pelagios, family Megachasmidae) from the Hawaiian Islands. Proceedings of the California Academy of Sciences (Series 4) v. 43

Basking shark

Aquatic scientific names in the news …

Basking shark

The first Basking shark sighting of 2016 has been reported off Cornwall. It was photographed in Mount’s Bay on Wednesday 6th July during a wildlife cruise.

456px-Cetorhinus_maximus_by_greg_skomalImage: Greg Skomal / NOAA Fisheries Service

The Basking shark is the second largest shark after the Whale shark and the biggest fish found in British waters, reportedly reaching lengths of around 12 metres. A planktivorous species that feeds close to the surface, passively filtering zooplankton, small fish, and invertebrates from the water, it is a seasonal visitor to British waters, usually arriving in significant numbers between May and October each year, in search of plankton blooms.

In winter, Basking sharks leave British waters and move offshore to depths of around 900 m to feed on deep-water plankton.

Cetorhinus maximus (Gunnerus, 1765)

Etymology.

Cetorhinus – Greek, Ceto, khtos (κητος), any sea monster, sea monster slain by Perseus (mythology), huge fish, whale; rhinus, rinos, ris (ρις), nose, snout – likely referring to the protuberant snout

maximus – Latin, greatest, largest – likely referring to overall size.

Great white shark

Aquatic scientific names in the news …

Great white shark

A Great white shark estimated to be around 7m in length was spotted about 200m offshore at Marino Rocks, near Adelaide,  Australia on Sunday 17th Jan. Local newspaper, The Advertiser, reported that a Westpac Lifesaver Rescue helicopter tried to herd the shark out to sea where it made its way into deeper water and that it had not been seen again.

The size of this fish puts it on a par with the fictional shark from the Jaws movies and, if accurate, makes it one of the largest Great whites to have been photographed; the average length of a mature specimen is likely to be around 4 – 5.2m with females being larger than males, the maximum total length for this species is subject to speculation and is often grossly exaggerated but the largest reliable record is 6.4m.

Great whiteImage: Shark Alerts SA (click to enlarge)

Shark Alerts South Australia, an organisation that reports shark sightings in South Australia for swimmers, surfers and other coastal water users, confirmed the estimated size using their six-metre jet boat to provide a comparison finding the shark to be larger.

Carcharodon carcharias (Linnaeus, 1758), the Great white shark or White pointer

Etymology.

Carcharodon – Greek, Carchar-, carcharos (καρχαρος), saw-like, jagged; -odon (οδον), odous (οδους), tooth; καρχαροδους, with saw-like teeth.
carcharias (καρχαριας) – Greek, shark, so called from its saw-like teeth.

Linnaeus’s original name for the species before it was moved to the more recent genus was Squalus carcharia (Squalus – Latin, a kind of sea-fish (classical); shark (scientific Latin)) – loosely speaking, shark with saw-like teeth.

In common with a number of other carnivorous shark species, those preying on other sharks, cetaceans (dolphins, porpoises, whales), and pinnipeds (seals and sea-lions) they have a combination of pointed lower teeth with broad triangular serrated upper teeth. The lower teeth allow for the prey to be gripped whilst the upper teeth with their serrated edges cut it into smaller easily swallowed pieces.