Coelacanth (Latimeria chalumnae)

Species: Coelacanth (Latimeria chalumnae)

Status: Critically Endangered (CR)

Interesting Fact: The coelacanth is a member of an ancient lineage that has been around for over 360 million years. It may be the closest living relative to the first creature to walk on land!

The enigmatic coelacanth was believed to have gone extinct with the dinosaurs until its remarkable rediscovery in 1938. Fossils have been found all over the world except for Antarctica. Living coelacanths have been found in deep submarine caverns, reefs and slopes in a number of locations off the coast of Africa.

Unlike any other living animal, coelacanths have a hinged joint in the skull allowing the front part of the head to be lifted whilst feeding on fish such as cardinal fish, eels and skates. Coelacanths also have a large gel-filled cavity in the head, called the rostral organ, which can detect electric fields and may be used to locate prey or monitor its surroundings. Coelacanths are ovoviviparous (young develop inside the mother), and females may give birth to up to 26 pups. They are long lived, being thought to survive for up to 80 years.  

The coelacanth is a difficult species to monitor. It is accidentally caught on lines whilst local fishermen search the deep waters for other species. A low reproductive rate means this species is particularly vulnerable to the removal of pregnant females from the population. The coelacanth is on listed Appendix I of CITES, and localised, voluntary bans on fishing protect areas where this species is known to inhabit.

Find out more about the coelacanth at the Australian Museum website.

See footage and images of the coelacanth on ARKive.

With thanks to @africanconserve for this suggested Endangered Species of the Week! If you would like to suggest an endangered species for us to profile, let us know via Twitter or Facebook.

Lauren Pascoe, ARKive Media Researcher

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Southern bluefin tuna (Thunnus maccoyii)

Species: Southern bluefin tuna (Thunnus maccoyii)

Status: Critically Endangered (CR)

Interesting fact: The southern bluefin tuna is one of the largest bony fish in the world, growing up to 4.3 metres long!

The southern bluefin tuna is an incredibly streamlined and powerful fish capable of reaching speeds of up to 70 km per hour through the water. Swimming together in shoals, the southern bluefin tuna migrates vast distances from the spawning grounds in the Indian Ocean to the feeding grounds in colder, southern waters. During the spawning period, a mature female will produce several million eggs. Southern bluefin tuna are opportunistic predators, feeding on a wide variety of other fish as well as crustaceans, cephalopods and other marine animals.

The southern bluefin tuna has been fished to the brink of extinction. Its flesh is highly prized in Japan, where an individual fish can fetch as much as 10,000 US dollars. The Commission for the Conservation of the Southern Bluefin Tuna was set up in 1994 to control the overfishing of this species; but some scientists believe more drastic measures need to be taken to save this species from extinction.

Find out more about this species on the Conservation of Southern Bluefin Tuna (CCSBT) website.

See this species on Google Earth.

See images and videos of the southern bluefin tuna on ARKive.

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Water is essential to all forms of life on Earth. That said, the enormous increase in the human population over the past few decades has placed a greater strain on the world’s freshwater reserves through direct consumption, agriculture and manufacturing activities. Sadly water shortages are not uncommon in many parts of the world. These shortages can have devastating effects for both people and wildlife and can be exacerbated by climate change.

The UN recognises March 22^nd as International World Water Day to encourage people to limit their use of water as well as to highlight the issue of water shortages. To mark the day, we thought we would highlight just a few of the many organisms that depend on freshwater for survival.

Water as a jealously guarded dive site

Blink and you could miss the all the action! A kingfisher emerges from the water victorious with its catch

The striking yet elusive kingfisher (Alcedo atthis) is famous for diving from its perch into rivers to catch fish and invertebrates. As the kingfisher requires a relatively large amount of food to sustain itself it will aggressively defend its watery hunting ground from other kingfishers with threatening displays and even physical contest. As kingfishers require clear water to see their prey and vegetation on which to perch, their presence is a good indicator of a healthy river ecosystem.

Water as a spawning ground and nursery

A mass of green-thighed frog frogspawn in freshwater

Amphibians depend on freshwater in some form or another to lay their eggs, which develop into fully aquatic tadpoles. Predation on tadpoles is often high which is why most species lay a large number of eggs in a specific breeding season. This strategy is practiced by the green-thighed frog maximising the amount of offspring that survive to adulthood.

Water as a last refuge

A pair of Cuban crocodiles in swamp habitat

The Cuban crocodile is found in only two freshwater swamps in Cuba. This extremely restricted range makes it highly vunerable to extinction and it depends on these specific habitats for its survival. Fortunately due to recent conservation efforts the Cuban crocodile’s numbers are recovering.

Water as a trap

The water boatman will make a meal out of any insects trapped on the surface of the water, like this dragon fly

A fierce predator in many ponds and lakes across Europe, the water boatman sits and waits near the surface of the water until it detects movement nearby… it then swoops in on its prey with a toxic bite!

Water as a place to grow

Growing from the deep: a white water-lily flower, view from underwater

Freshwater ponds and lakes all around the world are home to a huge array of interesting and beautiful plant life. The white water-lily has many adaptations to a life in freshwater such as its large flat leaves that float on the surface of the water so as to receive more light. Aquatic plants also often have important roles in freshwater ecosystems, oxygenating the water, provide nesting sites and keeping algal blooms under control.

Water as a place to set up a fortress

An American beaver swims with a tree branch

The American beaver is famous for drastically altering its freshwater surroundings to make a suitable habitat. Using its tough incisors to fell trees for dams, the beaver creates an area of open, still water where it constructs its lodge. Entrance to the lodge is only possible from under the water and therefore the beaver and any offspring are protected from terrestrial predators. The beaver itself also has specific adaptations for a life in water with webbed feet and a large flat tail used for propulsion as well as a dense underfur that keeps it warm even in freezing water.

Water as a hunting ground

A pike sheltering under water lily leaf

All ecosystems have a ‘top dog’ predator and in many rivers and creeks in Europe this will be the pike. A ferocious predator, the pike will remain perfectly still waiting for prey to come within a close distance and then move in for the kill with a lightening fast strike. Pike are likely to consider many of the animals in their watery environment as prey including fish, crayfish, frogs and newts and even ducklings and small mammals. Pike do need to be careful around members of their own species though as larger pike have been known to practice cannibalism!

Find out more about World Water Day 2012.

George Bradford, ARKive Media Researcher

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Remote camera traps are now being used underwater to study shark behaviour for conservation research.

The Caribbean reef shark has a relatively short, broadly rounded snout

From land to sea

During the last decade, camera traps have become a popular tool with biologists and conservationists to monitor land-based wildlife, particularly threatened and elusive species such as the snow leopard. Now, this technology has been put to use in an entirely different realm – the oceans.

Sharks, like their feline counterparts, are threatened top predators, so between 2005 and 2010, a team of marine biologists from New York’s Stony Brook University deployed underwater video camera traps in Belize to monitor the population of Caribbean reef sharks found there.

The idea behind the baited camera traps, nicknamed ‘chum cams’, was to find out whether Marine Protected Areas, where fishing is entirely prohibited, are home to more sharks than non-protected areas. In total, 200 cameras were placed both inside marine reserves and in fishing zones in the Caribbean Sea.

Bony fish and large crustaceans are among the preferred prey species of the Caribbean reef shark

Feeding on film

The smell of the bait, or ‘chum’, attracted sharks to the camera traps, which enabled scientists to record, count and compare the shark populations in two different marine reserves, Glover’s Reef and Caye Caulker, with those found in two fishing zones.

According to the research, published in the journal PLoS One, sharks were caught on film at nearly four times as many camera sites within the marine reserves as in non-protected areas. Data from tagged sharks also revealed that many sharks remain in the protected areas year-round.

“Although we know that relatively sedentary reef fish and lobsters benefit from marine reserves, this study now presents visual proof that large, active sharks are also dramatically more abundant inside these protected areas, too,” said Mark Bond, lead author of the paper and doctoral student at the Institute for Ocean Conservation Science.

“These areas provide the sharks and other coral reef species a respite from fishing, which means decreased fishing mortality for the sharks and more prey for them to eat.”

Caribbean reef shark injured by a fishing hook

Sharks at risk

In recent decades, populations of many shark species have suffered steep declines, with the lucrative trade in fins for shark fin soup being a key contributor. The Caribbean reef shark, which is intensively fished and is also often caught as bycatch, is currently listed as Near Threatened on the IUCN Red List.

“Our study demonstrates that marine reserves can help protect shark species that live on coral reefs. Moreover, the use of underwater video monitoring provides us with an excellent tool to determine if populations are recovering and thriving inside these reserves,” concludes co-author Ellen K. Pikitch, executive director of the Institute for Ocean Conservation Science.

Tiger shark

Ecotourism

Further shark research, this time surrounding the concept of ecotourism, was also published this week in the British Ecological Society’s journal Functional Ecology. This study, by scientists at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, revealed that the feeding of tiger sharks at offshore dive sites does not appear to adversely affect their behaviour.

Dive operations offering shark feeding tours have become a highly lucrative industry, and there were fears that feeding sharks could change the behaviour of the animals, making them more susceptible to threats. However, by using satellites to track the behaviour and movement of tiger sharks off Florida and in the Bahamas, the researchers discovered that this was not the case.

The researchers hypothesised that tiger sharks in the Bahamas, where chum is used to attract sharks for dives, would show restricted movements at the dive sites. However, the opposite was found to be true. Tiger sharks in the Bahamas site roamed over an area almost five times greater than tiger sharks in Florida, where the use of chum to attract sharks is illegal.

In a study conducted last year by co-author Neil Hammerschlag, results indicated that shark dive tourism generated more money for local economies than killing the animals for their fins.

He said, “Given the economic and conservation benefits, we believe managers should not prevent shark diving tourism out of hand until sufficient data were to demonstrate otherwise.”

Read more on this story at Mongabay.com – Camera traps go under the ocean, seeking sharks.

Read more about the shark and ecotourism story at CBC News – Ecotourism no threat to tiger shark behaviour.

Learn more about sharks on ARKive.

Kathryn Pintus, ARKive Species Text Author

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This week is Climate Week in the UK, and here at ARKive we thought we’d take the opportunity to highlight some amazing species and the different ways they may be affected by climate change. 

Common clownfish (Amphiprion ocellaris)

Species: Common clownfish                       (Amphiprion ocellaris)

Status: Not Assessed

Interesting Fact: The common clownfish can change from male to female!

Most famed for inspiring the character Nemo in the Walt Disney film ‘Finding Nemo’, the common clownfish is the most familiar of the clownfish species. Clownfish are the only fish known to be able to live amongst the tentacles of anemones. The tentacles of the anemones normally sting other fish, but clownfish excrete a mucus over their skin that protects them among the anemone’s tentacles. The anemone and clownfish live in a symbiotic relationship, with the clownfish feeding upon parasites and debris amongst the anemone’s tentacles, and in return scaring away animals that may prey upon the anemone. Clownfish are highly territorial, living in groups that guard their host anemone against other clownfish.

Climate Change: The greatest threat to the common clownfish is global climate change, which threatens this species through a combination of habitat loss, disruption of its senses and direct effects on its behaviour. Increases in ocean acidity levels have been shown to affect clownfishes’ ability to detect the chemical signals necessary for navigating to anemones.

For more information on climate change, visit ARKive’s climate change pages.

Take part in ARKive’s Creative Climate Change Challenge or find out how you can get involved in Climate Week.

View images of the common clownfish on ARKive.

Becky Moran, ARKive Species Text Author

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