Tag Archives: creature of the month

The Beautiful but Deadly Lionfish is the Creature of the Month

Lionfish, genus Pterois, is very popular amongst those with aquariums, and this trade may have led to them being described as amongst some of the most aggressively invasive species on the planet. Lionfish are native to the Red Sea, Pacific Ocean, and Indian Ocean, most often found around corals, reefs and rocky surfaces down to about 50 m. They have quite a distinctive appearance with their red and white stripes, together with large spiky dorsal fin rays containing venom for defence against predators. They don’t appear to have many natural predators, but large Groupers and Moray eels have been observed feeding on them.

Clearfin lionfish, Pterois radiata
Clearfin Lionfish, Pterois radiata
By The High Fin Sperm Whale [CC BY-SA 3.0]

Lionfish can live 15 years and reach 45cm (17.7in) in length. They have several adaptations, the most dangerous being the venom contained in the dorsal fin rays that can be hazardous to divers. This venom can cause nausea, dizziness, breathing difficulties, and in some rare cases, limb paralysis and death but are only harmful if you come into contact with it. Juveniles also show a unique adaptation, they possess a tentacle above their eye sockets that is thought might be used to either attract prey or in sexual selection.

For food Lionfish tend to prey on almost anything they can find, small fish, invertebrates, molluscs and the larger ones may even prey on juvenile lionfish. Some have been found with up to 6 different species of prey in their stomachs. In hunting prey, it is believed they shoot out jets of water to disorientate or stun their meals.

Lion Fish in Red Sea by Tim Nicholson
Common Lionfish, Pterois miles by Tim Nicholson

Outside aquarium circles, Lionfish are perhaps most famous for the speed in which they have invaded the east coast of the Americas, stretching from the Delaware Bay down to Brazilian waters and everywhere in between. It is thought, due to their resemblance to the species found in the Philippians, Lionfish where likely introduced into the Atlantic waters from private owners who found they could no longer look after their pets when they became too big. They don’t like to play nice with other fish either. They quite often show a hostile attitude towards others and are fiercely territorial, much to the detriment of other reef fish. This hostile attitude along with no natural predators does not bode well for the Atlantic reefs, where studies in the Bahamas have shown that Lionfish could be responsible for a decrease of up to 80% of reef diversity.

Lion Fish in USA by Paula Whitfield
Lionfish about 40 miles off the North Carolina coast by Paula Whitfield

To control the invasive populations of P. Volitans and P. Miles, several avenues have been explored. Spearing of the Lionfish has been legalised in some countries with a few even organising ‘derbies’ to control numbers. One other novel approach is to try and promote their meat for human consumption, which can apparently be quite tasty if you’re brave enough to try!

Conger Eel is the Creature of the Month

The conger eel has the easiest-to-remember Latin name of them all: Conger conger. This massive fish can grow to almost 3 m (10 ft) long, the females often being bigger than the males.

Distinctive in shape, the conger lacks scales and has one long fin which stretches from behind the head, all along the body and round the tail to underneath its body. This fin is actually a fusion of the dorsal, tail and anal fins.

Conger eels are widespread. You find them in the Eastern Atlantic from Iceland to Senegal, in the Mediterranean and in the Black Sea. They like to hide in holes and crevices. At night they hunt fish and crustaceans like crabs and lobsters. In spite of this divers often see crustaceans sharing a hole with a conger. If you look closely at the photo above you can see squat lobster alongside the eel.

Conger Eel

Congers breed only once in their lives, at between 5 and 15 years of age. They migrate to deep water to spawn – some sources say as deep as 4000 m – in one or more areas between Gibraltar and the Azores in the mid-Atlantic. After spawning they die, their larvae drifting back into coastal waters.

Evidence suggests that the eels are being over-fished, but they have not yet been assessed by the IUCN.

Conger eels are very strong and have been known to attack divers. However, they are docile unless provoked.

Further Reading

Great British Marine Animals by Paul Naylor

The Marine Life Information Network

Population structure and connectivity of the European conger eel
(Conger conger) across the north-eastern Atlantic and western
Mediterranean: integrating molecular and otolith elemental
approaches. Mar Biol (2012) 159:1509–1525, Alberto T. Correia et al.

Photos by Tim Nicholson, whose books and photos are available from http://www.photoboxgallery.com/timnicholson

Creature of the Month, Harlequin Shrimp, eats Starfish Alive

Harlequin shrimps spend their lives in monogamous pairs, working together to trap their favourite food: starfish. They find the starfish by smelling with their antennae, then the two of them turn the much bigger animal over and feast on its tube feet. Sometimes they will take the starfish into a dark recess of their reef territory, where they will eat it alive over several days.

Exquisitely patterned, Harlequin shrimp grow to 5 cm. Two species claim the name of Harlequin Shrimp: Hymenocera elegans and Hymenocera picta. They look similar, but the former lives in the shallows of the Red Sea to Indonesia; you find the latter more easterly in the Pacific.

Harlequin shrimp are a favourite with underwater photographers. Once you spot one it is easy to photograph, but they are uncommon and so take some spotting in the first place.

Further Reading:
The Blue Planet, BBC Publications, 2001
Diving – Enjoy, Not Destroy

Photo credit: Copyright www.tommyschultz.com

Manta Ray is Creature of the Month

Until recently there was thought to be only one species of Manta Ray: Manta birostris. Now though, researchers have observed that there are actually two: the Reef Manta Ray (Manta alfredi) and the Giant Manta Ray (Manta birostris). Both of these species have been classified as vulnerable in the IUCN Red List which was published this month.

Growing to more than seven meters across, the Giant Manta Ray is the largest living ray and a very impressive sight underwater. The Reef Manta Ray is smaller but still reaches 5 m across.

Mantas migrate vast distances, crossing international boundaries, in search of food. Products from manta rays have a high value in international markets, and targeted fisheries hunt them for their valuable gill rakers used in traditional Chinese medicine. Monitoring and regulation of the exploitation and trade of both manta ray species is urgently needed, as well as protection of key habitats.

Both species of Manta are found around the globe, their ranges overlapping in some places like Mozambique. It is difficult for a diver to distinguish between the two species. Both can be shades of black or white. They are also sometimes confused with the devil rays of the genus Mobula.

Completely harmless filter-feeders, Mantas use their head fins to direct plankton into their mouths. As plankton occur near the surface of the seas, that’s where Mantas are also found. Filtering your food out of the oceans doesn’t take much energy, which is why Manta rays can be so large.

The Giant Manta Ray appears to be a seasonal visitor to coastal or offshore sites. While this species seems more solitary than the Reef Manta Ray, Giant Manta Rays are often seen aggregating in large numbers to feed, mate, or clean. Sightings of these giant rays are often seasonal or sporadic but in a few locations their presence is a more common occurrence. At certain times of the year you can see the Giant Manta Ray at aggregation sites such as the Similan Islands, Thailand; northeast North Island, New Zealand; Laje de Santos Marine Park, Brazil; Isla de la Plata, Ecuador; Cocos Island, Costa Rica; and Isla Holbox, Mexico. Being oceanic, you see them less frequently than the Reef Manta Ray.

The Reef Manta Ray is found from the Sinai Peninsula in the Red Sea to Durban, South Africa in the Western Indian Ocean, and from Thailand to waters off Perth, Western Australia in the Eastern Indian Ocean. Reef Manta Rays do not commonly venture from coastal waters, often moving between inshore cleaning stations and feeding areas. The Reef Manta Ray can reach 5 m across, however, in most mature individuals do not exceed 4 m.

Another factor which adds to the vulnerability of the Manta ray is its low reproductive rate. In the wild, females bear on average only a single pup every two to three years. Female mantas are thought to mature at around 8 to 10 years of age and to live to around 40 years.

Dive tourism involving Mantas is a growing industry and can significantly enhance the economic value of such species in comparison to short-term returns from fishing. However, tourism related industries can also negatively impact individual behaviour, entire populations and critical habitat. Tourism needs to be developed responsibly, with the needs of the animals respected.

Manta and devil ray catch increased from 900 tonnes to over 3,300 tonnes between 2000 and 2007.

Further Reading:
Red List: Reef Manta Ray, Manta alfredi
Red List: Giant Manta Ray, Manta birostris
Coral Reef Guide Red Sea by Ewald Lieske and Robert F. Myers

Blue-Ringed Octopus, one of the World’s most Venomous Animals, is Creature of the Month

The blue-ringed octopus – Hapalochlaena lunulata – is said to carry enough venom to kill 26 people. These small animals spend much of their time in hiding, camouflaged. But when disturbed, the octopus will flash around 60 beautifully iridescent blue rings and, when strongly harassed, bite and deliver a neurotoxin in its saliva. Don’t pick one up!

The flashes are extremely fast: much faster than generally seen with octopus. According to a study published in November’s Journal of Experimental Biology, the octopus achieves the fast flashes using muscles under direct neural control. “A fast, conspicuous display…is an advantage to predators, who are warned before attacking a venomous creature, and of course to the octopus itself, as it avoids being eaten.” says zoologist Lydia Mathger and lead author of the study.

Blue-ringed octopus live in tide pools and coral reefs in the Pacific and Indian Oceans, from Japan to Australia. There are around 10 different species, all very small. While resting, this blue-ringed octopus is a pale brown to yellow color depending on its surroundings.

Two types of poison secreted by two separate poison glands are used against prey and predators. One of the poisons is used for hunting crab, the other, the extremely toxic one, is used as self defence against predators.

The octopus’s parrot-like beak easily penetrates a websuit. Their venomous saliva can have dramatic effects within 15 minutes. For the first few minutes, though, if you are bitten you may feel no discomfort. Any close contact with this octopus should be treated as life-threatening immediately, as there is no antidote.

Further Reading:

How does the blue-ringed octopus (Hapalochlaena lunulata) flash its blue rings?
doi: 10.1242/?jeb.076869 November 1, 2012 J Exp Biol 215, 3752-3757.

J. Exp. Biol. 2012 215:i-ii.

Venomous Animals of the World, Steve Backshall

Crown Butterflyfish is Creature of the Month

Found only in the Red Sea and Gulf of Aden, the Crown Butterflyfish (Chaetodon paucifasciatus) lives between 4 and 30 m. You can spot it by its distinctive red rear, but its key identification feature is the yellow stripe through the eye.

This species is the most common of all the butterflyfish along the Jordanian, Egyptian and Saudi Arabian coasts.

The Crown Butterfly fish likes to live around hard corals: an abundance of these fish indicates good hard coral coverage on the seabed. A scarcity in a previously abundant area, though, signals that the coral may be in trouble.

The Butterfly fish family or Chaetodontidae are small, colourful fishes with a continuous dorsal fin. Chaetodontidae comes from the Greek, meaning bristle teeth, and indeed they do have small, brush-like teeth. Most species are active during the day, resting among corals or rocks at night.

Some species feed on coral polyps, and these tend to be territorial. When part of a coral is attacked in this way, the surrounding polyps often withdraw as far as they can into their protective skeletons. The fish then has to move further along the reef.

Further Reading

  • Coral Reef Fishes, Indo-Pacific and Caribbean, Ewald Lieske and Robert Myers
  • Khalaf, M. and Crosby, M. P. (2005), Assemblage structure of butterflyfishes and their use as indicators of Gulf of Aqaba benthic habitat in Jordan. Aquatic Conserv: Mar. Freshw. Ecosyst., 15: S27–S43. doi: 10.1002/aqc.698
  • Khalaf, M. A. and Abdallah, M. (2005), Community structure of butterflyfishes in the Red Sea and Gulf of Aden. Aquatic Conserv: Mar. Freshw. Ecosyst., 15: S77–S89. doi: 10.1002/aqc.708

Midnight Snapper is Creature of the Month

Bright yellow eyes distinguish the Midnight Snapper (Macolor macularis) from related species. You find it in the Western Pacific between 3 and 50 m, from the Maldives to the Solomon Islands and Ryukyu Islands to New Caledonia.

Juveniles look very different to adults: they are black and white with blotches on their backs and stripes below. They live solitarily on protected reef slopes with feather stars, in staghorn corals or large sponges. When adult Midnight Snapper sometimes aggregate in groups and live on seaward reefs. They feed on large zooplankton at night.

Juvenile Midnight Snapper

In spite of the abundance of adults, the distinctive juveniles are not similarly common on coral reefs. One explanation is that the adults have a long life-span, but the survival of their larvae is seldom successful. In fact Macolor species live 40 to 50 years on the Great Barrier Reef, which would support this theory.1

The Midnight Snapper is also known as the Black and White Snapper, which is confusing as the similar species Macolor niger is also sometimes known by this name.

The photo is taken on Kihadoo Ridge (Baa Atoll), Maldives.

Further Reading:
Froese, R. and D. Pauly. Editors. 2011. FishBase.
1The Pelagic Larva of the Midnight Snapper, Macolor macularis (Teleostei: Lutjanidae), Amanda C. Hay and Jeffrey M. Leis Records of the Australian Museum (2011) Vol. 63: 85-88.

More photos of Midnight Snapper…

Tassled Scorpionfish is Creature of the Month

The scorpionfish is one of the most venomous fish in the world. It has several spines linked to venom glands. The poison causes severe pain and paralysis.

From earliest times fishermen have believed in the efficacy of the liver and flesh of scorpionfish applied as an antidote to the wound from the animal. In his 1943 book, Sting-Fish and Seafarer, H M Evans recommends injecting crystals of permanganate of potash to alleviate a scorpionfish sting. This is not found in your average diver’s first aid kit these days. Instead immerse the wound in very hot water and get medical help as soon as possible.

The scorpionfish is extremely well-camouflaged. It can change colour to match its background and has many “tassles” masking its outline. This Tassled Scorpionfish, Scorpaenopsis oxycephala, lives from 1 to at least 35 m in the Red Sea and Indo-Pacific. Lacking a swim bladder, it remains on or near the bottom. Lethargically, the fish waits for prey to pass by then opens its lower jaw and sucks its victim in.

Not many animals prey on the scorpionfish, its venom deterring most. A fully grown octopus though does not seem to be affected by the spines and will envelop and eat the scorpionfish.

Mauve Stinger is Creature of the Month

The Mauve Stinger, or Luminescent Jellyfish, is a beautiful jellyfish. Often coloured purple, you can find it around the world in warm and temperate waters from around 12 to 30 m.

This jellyfish is the most venomous in the Mediterranean. However, its sting is usually limited to the skin surface with local pain which lasts for one to two weeks. In some cases the sting can leave scars, or pigmentation of the skin lasting for several years. Should you be stung by a jellyfish, rinse the area with vinegar for 30 minutes. If vinegar is not available use sea water: don’t use fresh water. Remove any tentacles left on the skin.

As the name suggests, the luminescent jellyfish gives off light. When water is disturbed by waves, or a ship, the jellyfish flashes attractively for a short while.

The jellyfish can move vertically, but are unable to propel themselves horizontally and so are carried by currents. They move up and down in response to migrations of their prey, zooplankton.

Intestingly, a group of jellyfish have their own collective noun, in fact they have two: a “smack” or a “fluther” of jellyfish.

Further Reading:

Mariottini, G.L.; Giacco, E.; Pane, L. The Mauve Stinger Pelagia noctiluca (Forsskål, 1775). Distribution, Ecology, Toxicity and Epidemiology of Stings.. Mar. Drugs 2008, 6, 496-513.

Jellyfish blooms move food energy from fish to bacteria

Creature of the Month: Giant Mussel, Pinna nobilis

The rare giant mussel, Pinna nobilis, is found only in the Mediterranean Sea. It is one of the largest bivalves in the world, growing to 120 cm long. The mussels can live for as long as 20 years. It sticks up out of the sea bed so is easily seen when diving, once you know what to look for.

Pinna nobilis has been assessed by the European Union as being in need of special protection (EC Habitats Directive). This means that it is illegal to kill or disturb the species. However, studies have found that in Greece many individuals are killed by fishing. The mussels were poached exclusively by free-divers and fishing mortality was practically zero at depths below 9 m, where the visibility was very bad. Because of this large individuals were restricted to deeper areas.

In another study, this time off Italy, divers found that the giant mussels were managing to hold their own, in spite of all the difficulties of a degraded and heavily polluted environment and the damages of illegal fishing.

Depending on area, the mussels live between about depths of 3 and 60 m. In the Italian study divers didn’t find any below 16 m. In the Adriatic Sea, they are found down to 30 m. They live singly, not in large groups like the mussels we are used to. At best the Italian study found only one every 1.4 hectares (3.5 acres).

The giant bivalve lives on soft bottoms: sand, seagrass meadows and mud. If you find what looks like a small specimen growing on a rock it is probably not P. nobilis but the more common P. rudis.

More news stories on Pinna nobilis