chondrichthyes

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Blacktip Reef Shark (Carcharhinus melanopterus)

Photos taken by Connor Butler - Tioman Island, Malaysia. 

Species in the Rhinochimaera family are known as long-nosed chimaeras. Their unusually long snouts (compared to other chimaeras) have sensory nerves that allow the fish to find food. Also, their first dorsal fin contains a mildly venomous spine that is used defensively. They are found in deep, temperate and tropical waters between 200 to 2,000 m in depth, and can grow to be up to 140 cm (4.5 ft) in length.

Chimaeras (also known as ghost sharks and ratfish) are an order of cartilaginous fish most closely related to sharks, but they have been evolutionarily isolated from them for over 400 million years.

(Info from WP and .gif from video by NOAA's Okeanos Explorer—this is not an animation!)

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Tasselled Wobbegong (Eucrossorhinus dasypogon)

…a species of carpet shark that is found in coral reefs off northern Australia, New Guinea and surrounding islands. Tasselled wobbegongs are considered to be one of the most specialized wobbegongs as their coloration and dermal fringe gives them excellent camouflage. They are active at night and spend their days lying motionless in caves or ledges. At night they will swim onto the reef to hunt fish (both bony and cartilaginous), crustaceans and cephalopods.

Tasselled wobbegongs are ambush predators and are known to let small fish and crustaceans rest on top of them, they in turn attract larger fish which the wobbegong attacks. They have also been observed wiggling their tail back and forth when food is nearby, their caudal fin resembles a small fish and this is thought to be a way for them to attract prey. 

The tasselled wobbegong is currently listed as near threatened. This is mostly due to pollution, habitat degradation and blast fishing.

Phylogeny

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Orectolobiformes-Orectolobidae-Eussorhinus-E.dasypogon

Images: Jon Hanson and Leonard Low

Halmahera Epaulette Shark (Hemiscyllium halmahera)

…a species of Bamboo Shark (Hemiscylliidae) which is known from Indonesia. It is described from two specimens collected near Ternate Island in 2013, off the coast of Halmahera island from which it gets its common name. It is very similar in appearance to the similar H. galei which occurs in West Papua but differs in spot patterning. H. galei has seven large, dark spots on each side of its body, H. halmahera has a brown color with clusters of brown or white spots

Classification

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Orectolobiformes-Hemiscylliidae-Hemiscyllium-H. halmahera

Image: Mark Erdmann 

Shocked Shark by Will Clark / Underwater Photographer of the Year 2016

“This juvenile blue shark was the first to arrive at our boat after an hour of chumming. We were alerted to its presence by the bobbing of a small buoy which had fresh mackerel tied to it. I leaned over the side of the boat with my camera housing not quite fully submerged as the skipper tried to coax the shark nearer to the boat. He got the blue very close to me, and then just at the last moment he whipped the bait out of the water, which got this reaction from the shark.”

Whitesaddled Catshark (Scyliorhinus hesperius)

…a species of Catshark (Scyliorhinidae) which inhabits the upper continental slope of the western central Atlantic, from the Honduras, Panama, and Colombia, between latitudes 22° N and 9° N,. Whitesaddled catsharks will inhabit depths between 275 and 460 m and likely feed on a range of small fish and invertebrates. 

Classification

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Selachimorpha-Carcharhinifomres-Scyliorhinidae-Scyliorhinus-S. hesperius

Image: NOAA

youtube

ICYMI: Researchers tagging the endangered smalltooth sawfish (Pristis pectinata) in the Bahamas became the first to record a sawfish birth in the wild.

Japanese Sawshark (Pristiophorus japonicus)

…a species of sawshark (Pristiophoridae) which occurs in the northwest Pacific Ocean around Japan, Korea, and northern China, where it inhabits the sandy or muddy bottoms of the continental shelves (at depths of 50-800 m). Japanese sawsharks are primarily “benthic” and will feed on a wide range of small bottom dwelling invertebrates and fish. 

Classification

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Pristiophoriformes-Pristiophoridae-Pristiophorus-P. japonicus

Image: Opencago.info

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As a scientist who studies blacktip sharks, I feel like it is my duty to inform others about this common case of misidentification.

The first picture is of one of my sharks, and the second picture is another species within its genus for which my shark is mistaken. Many people do not know that the blacktip (Carcharhinus limbatus) and blacktip reef shark (Carcharhinus melanopterus) are two completely different species. First, the blacktip reef is found in the Indian and Pacific oceans, and they have limited ranges as they stay extremely close to their sites for many years. Conversely, the blacktip is worldwide along coastlines and migrates seasonally. As for visual differences, the black fin markings on the blacktip reef are much more prominant. The blacktips nearly always lack black tips on their anal fins, and their black markings fade significantly with age. Another notable distinction is coloring, as blacktips tend to have a gray/bronze coloring while blacktips are a paler, cream based color. A behavioral difference is that blacktips have been known to jump out of the water like a spinner shark (Carcharhinus brevipinna) in the presence of prey or when caught on a line (I have witnessed this first-hand when I caught my first juvenile). Genetically, the blacktip is actually thought to be most closely related to the blacknose (Carcharhinus acronotus) based on DNA studies. However, resolution of phylogenies for both species is far from happening.

There are two lesser known species (Australian blacktip and smoothtooth blacktip) that are not as easily distinguished. The Australian blacktip (Carcharhinus tilstoni) looks exactly like the blacktip and was only found to be a separate species due to genetic analysis and vertebral differences; it is found along the northern half of Australia’s coastline. The smoothtooth blacktip (Carcharhinus leiodon) looks like the blacktip reef shark and is exclusively found along the Arabian Peninsula coastline.

To the ancient past, I raise my voice.
To the ancient past, I cry.

Kingdom Animalia,
Phylum Chordata,
Class Chondrichthyes,  
Genus Carcharocles,
Species Megalodon.

To great Ancestor Megalodon,
the Swallower of Whales,  
Mighty-Jaw and Great-of-Tooth, I call.
Show your teeth this night, and with them tear asunder the wicked man.
Show your teeth to him, and to those who are like him.

Kingdom Animalia
Phylum Chordata
Class Osteichthyes
Genus Tiktaalik
Species Roseae

To gentle Ancestor Tiktaalik,
the Fish-Who-Walked,
Great Traveler and Pioneer, I call.
Walk with my country, my people, tonight.
Walk beside us through this darkness, walk with us towards the light.

Kingdom Animalia
Phylum Chordata
Class Mammalia
Genus Juramaia
Species Sinensis

To nurturing Ancestor Juramaia, 
the Placental Mother,
She of the Womb and Umbilical Cord, I call.
Hold us close this night, and shelter us as you shelter your growing offspring.
Hold our hands as we strain with the birth-pains of change, and let our suffering be worth it in the end.

To the spirits of my most ancient ancestors, I cry.
To the spirits of the Fossilized, I lift up my voice.
Protect us, guide us, nurture us.

This is my prayer. This is my plea.
Spirits of the ancient past, be with me tonight.