One of the most popular must-have items this year for any spatial ecologist goes under the street name of “Tags”. Tags cover a wide array of devices that allow scientists, and now even the public, to track the movements of an animal in space and time. Knowledge of animal space use is fundamental in establishing conservation and management policies….especially when animals under-go large-scale migrations.

 Acoustic Tags

Transmit coded sounds that are typically detected by an array of transceivers or listening stations. They can either be worn externally or surgically implanted into the animal.

Accelerometer Tags

Record the 3-dimensional movements and orientation of an animal as it goes about its daily business. Scientists are then able to construct fine scale movement tracks of those animals, which enable studies on aspects such as energetics.

PAT or PSAT Tags

PSAT stands for ‘pop-up satellite archival tag’ and it pretty much does exactly what it says on the tin. The tag is attached externally to an animal and will store data such as depth, temperature, sunrise and sunset. Then, at a predetermined date, the tag will pop-off, float to the surface and relay its archived information back to satellites. Using the time of sunrise and sunset and depth, scientists are able to estimate its location (Light based geolocation).

SPOT/SAT tags

‘Smart position only tags’ (SPOT) or satellite tags make use of the Argos satellite system and the scientific principle of Doppler shift to accurately geo-locate the tag. These tags must be able to “see” the satellites, so are only suitable for animals that spend a lot of time on the surface.

GPS (Global Positioning System)

Using a system similar to the ones you find in your smart-phones and satnavs, these tags are able to geo-locate the animal depending on the position and orientation of numerous satellites orbiting the earth. Like the SPOT tags, they are only suitable for animals that spend a lot of time on the surface.

Crittercams

Developed by National Geographic, this light weight camera is attached to the animal and records live footage as well as temperature, depth and acceleration. Crittercams have enabled scientists to directly witness specific behaviours and interactions in the real world.

Sharkcam

The latest in must have autonomous animal tracking; this autonomous underwater vehicle (AUV) will follow any animal with a transmitter tag on it. Collecting a wide range of data as it follows its target, this surely is the must have gadget for this year. The video below is of it tracking a white shark in 2013; that is until the AUV then becomes the one that is being followed.

This wearable tech’ is allowing scientists to uncover previously unknown movements of many marine animals. You too can even log on to various websites and follow animals yourself.

Follow sharks with OCEARCH: http://www.ocearch.org/

Follow sharks, turtles, birds, sea lions and many more at: http://www.seaturtle.org.uk/tracking/

Guy Harvey marine life tracking: http://www.nova.edu/ocean/ghri/tracking/

Tags are attached with minimal effect to the animal, because after all, we want to observe natural movements. There are strict weight restrictions that need to been adhered to in order not to impede animal movement. Many of these tags will errode off the animal over time or are manually removed by scientists at the end of the study period. The animals’ welfare is the number one priority to research scientist working with animal movements.

Knowledge of animal movement patterns is fundamental for the effective implementation of conservation and management practices. How are we supposed to protect an animal if we don’t know the extent of its movements? Tags are designed and attached in order to be as “neutral” as possible on the animal with ethics and welfare being a main priority. The culmination of technology, engineering, mathematics and biology has revealed great insights into the secret lives of marine animals. This is the wearable tech’ that really matters. Yeah, ok…it may not look the most attractive, but the results they produce have huge implications for the way that we perceive and subsequently try to protect the animals that wear them.

What are your thoughts? I would love to hear them and would invite you to join the discussions below.

Christopher Bird (@SharkDevocean)

The post Wearable Wildlife Tech appeared first on Exploring our Oceans .

When most people think of sharks they think of white sharks breaching and tiger sharks in crystal clear Bahamian waters. So when a rare deep-sea megamouth shark (Megachasma pelagios) washed up in the Philippines early this year, I had a lot of people contacting me asking if it was even real. You bet your bottom dollar it was real and here are some facts and photo’s to stimulate your inquisitive brains.

1. Only discovered in 1976

It was first discovered in Hawaii, just 38 years ago, in 1976 after accidently being caught in a deep-sea anchor. The large 4.46m shark was eventually transported to the National Marine Fisheries Service where it was later confirmed that neither the genus or species had previously been described.

2. Huge gaping of the sea

The scientific name Megachasma pelagios, translates from Latin into, huge (mega) gaping or yawning (chasma) of the sea (pelagios).

3. Only 59 documented sightings

As of writing this post, 06 July 2014, only 59 confirmed sightings have been documented (the 59^th being the sighting last week in the Philippines). Most sightings have been in Taiwan, Japan and Philippines, and are usually a consequence of by-catch. They have also been found in the Atlantic, Indian and Pacific Oceans. A full list of the 59 megamouths can be found here.

4. Can reach nearly 6m long

The largest confirmed speciemen was a carcass found in Taiwan that measured a whopping 5.8m (~19 feet) but there have been suggestions that they can reach even bigger than this.

5. Closest relative is the thresher shark

Megamouths closest living relative is actually the thresher shark but you wouldn’t think it on looks alone.

7. Planktivorous engulfment feeder

The megamouth shark is one of only three known plankton feeding sharks, including the basking shark (Cetorhinus maximus) and the whale shark (Rhincodon typus). Whilst it was initially believed that this shark would suck in its mainly krill based diet, it is now believed that it performs engulfment feeding. Engulfment feeding is typical of baleen whales but this is the only species of shark that is thought to use this mechanism to feed [3].

8. Bioluminescent assisted feeding

It is believed that the slow swimming megamouth shark may make use of a highly reflective, luminescent mouth, which may act as a light trap to attract prey (imagine its mouth like an underwater electric flytrap found in kitchens). It has also been proposed that a bioluminescent strip above the mouth may also be used in a similar way, although neither of these behaviours have been proven.

9. Automatic electronic food detectors 

Although they have the lowest abundance ampullary pores (electro-sensory organs) of any described shark, the arrangement of the pores “would allow for the detection of planktonic organisms around the head as the shark swims through the water (horizontally and vertically).”

10. Twilight inspired movements

By acoustically tracking an individual shark in 1990, scientists were able to ascertain that this mysterious shark undertakes crepuscular (occurring during dusk and dawn) vertical migrations. During the daytime, the shark spent most of its time in deeper waters (400-500m) then at night, migrated to shallower waters. This behavior, often termed “diel vertical migration”, is common in other sharks and is typically associated with the following of prey items that adopt similar movements.

11. Preyed on by sharks and whales

Documented predators of the megamouth shark include sperm whales, orcas and other sharks. Various specimens have also washed ashore with circular shaped wounds torn from their flesh, which is typically indicative off cookiecutter shark predation.

12. Best way to be eaten is battered and deep fried. 

After processing the 7^th  ever recorded megamouth shark specimen in 1995, researchers couldn’t resist the temptation of tasting a piece of this mystery creature they had just dissected and analysed. They were subsequently treated to 3 different preparations of some dorsal muscle. Battered & fried is apparently the best way to eat this shark!! [7]

“The next day Director Wakisaka had megamouth prepared, from a small piece of dorsal muscle, as a final treat for Jose and Genie: fried, poached with French sauce, and tempura style. Tempura was best”.

So that is the Megamouth shark. Rare, elusive, mysterious, plankton feeding giant of the deep.

For me the megamouth shark is the perfect poster child for deep-sea mysteries. It is quite outstanding that in days of such high fishing pressures, this shark has remained, at most, hidden from the public eye. It does make you think how many other creatures there are in the deep-sea that we still don’t know about. (and before you say it, no this does not mean Megalodon could still be alive. It just simply isn’t).

Christopher Bird

(Twitter: @SharkDevocean)

The post Introducing: The Megamouth Shark appeared first on Exploring our Oceans .

By Christopher Bird (@SharkDevocean)

Some estimates suggest that 80-90% of all deep-sea creatures can produce their own light, in a process called bioluminescence. If you thought the deep-sea was a dark, lifeless expanse, think again. The diverse range of crabs, squid, jellyfish and fish emitting light must make the deep-sea look more like a scene from Star Wars than anything earth bound. Most of these creatures use light in one of three ways:

1. To avoid being eaten.
2. To acquire food through attracting prey.
3. To communicate with members of same species.

How it works:

Light organs, called photophores (in latin; light carrier), can work in one of two ways. Some fish harness the light produced by symbiotic bacterium that they engulf (passive), while others are able to produce their own light through internal chemical reactions. The deep-sea sharks, however, use a different method all together.

Shark System:

Deep-sea sharks use a combination of hormones and neurotransmitters. Hormones melatonin and prolactin are responsible for short-term glows (20-60 mins) and long term glowing (several hours), respectively. Some species of lantern shark even go as far as to have bizarre hair-like skin denticles to maximise light emittance (It gives them an almost furry feel, nawhhhhh).

The Sharks:

There are only two families of deep-sea sharks that are able to glow in the dark. They are the Kitefin sharks (Dalatiidae) and (as the name suggests) the Lantern sharks (Etmopteridae). These two groups account for about 12% of all described shark species (>50 species). These small deep-sea sharks are incredibly diverse and can be found in all of the world’s oceans, apart from polar seas (a little too cold for these guys it would seem).

Camouflage: 

The majority of photophores are concentrated on the underside of the shark and it is now understood that they are used for camouflage. Now you may be thinking it seems counterintuitive to use light in the darkness of the deep-sea for camouflage; surely any light omitted would be like a flashing light for a free dinner. The opposite is true however.

Whilst the deep sea is relatively dark, residual light can still be seen penetrating from above. Using a process called “counter-illumination”, sharks are able to obliterate their silhouette from this residual down-welling light, thus making them invisible to predators from below (Its almost like an invisibility cloak for sharks).

Now here is where, at least I think, it gets even more interesting. The light produced from the photophores is of a relatively constant intensity. But Chris, how do the sharks stay camouflaged when light levels change? Great question, you inquisitive reader; it has been hypothesised that these sharks will actually migrate to different depths throughout the day to match their own light with that of the environment. This means that during the day, at high levels of light, these glow-in-the-dark sharks will have to be at deeper depths to remain camouflaged. They will then migrate to shallower depths at night to remain cryptic…crafty little ninja sharks!!

Other uses:

For the majority of kitefin sharks, photophores only serves as camoflauge. There is however an exception to this case, but more on that later. The lantern sharks, however, display a more complex and diverse range of photophore zonation and pattering.

1. ID lights: The presence and distribution of glowing cells on the side of the shark is unique to that species (“la” in image below). This has lead scientists to believe that these glowing strips are used to help sharks identify members of the same species.
2. Glowing genitals: In some species of lantern shark, the photophores associated with the genitals, help sharks identify members of the opposite sex (“ie” in image below). Very useful when trying to have procreative sex in the dark!
3. Love handles: A light strip on the pectoral fins (“Pe” in image below) of females helps males bite down and latch on during copulation. This minimises the amount of fumbling around.
4. LIGHTSABERS!! Light organs are located on the dorsal fin (“SAPs” in image below) behind transparent dorsal fin spines. The now glowing lightsabers, I mean fin spines, act as a visual deterrent for any potential predation attempts.

 The mysterious dog collar

The cookie cutter shark (Isistius brasiliensis), like other members of the Dalatiidae family, only has photophores on its underside. Unlike other counter-illuminating sharks however, the cookiecutter has a banded area near its “neck” that is devoid of light emitting cells. The dark area is often referred to as a “dog-collar” due to its appearance. Now, for some time, this area has been speculated to act as a prey attractant. By splitting up it’s glowing regions into two groups, large predatory fish would be attracted to the shark. The cookie cutter could then bite onto the “predator” and leave it’s distinctive cookie-like hole, tagged on its side. This has recently been brought into question though.

The usual prey items of the cookie cutter are megafauna such as whales, dolphins, seals and tuna. These large animals are either filter-feeders, and would thus not be attracted to a smaller glowing “fish”, or are of a large enough size that breaking the glowing region up into two pieces would be unimportant. It is now thought that this “dog collar” may actually be used as a form of social recognition among cookie cutters.

So, just when you thought sharks couldn’t get more fascinating, the deep-sea glow-in-the-dark sharks show us how much more badass they can be. Deep-sea sharks generally get less attention than their larger, shallow cousins. Can a white shark glow in the dark? No! Does a tiger shark use lightsabers to fend off predators? No! And do hammerheads have glowing genitals? Errr No!

So next time you think about sharks, of course think about the large pelagic/coastal species (they are amazing in their own right) but maybe give the fascinatingly diverse groups of glowing deep sea sharks a thought. With this new found love for glow in the dark sharks, I’m expecting big things from fancy dress and pumpkin carving this Halloween!

Christopher Bird

Twitter: @Shark Devocean

N.B. Any image not taken by myself has been credited and hyperlinked to source.

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