POTENTIALLY HAZARDOUS MARINE LIFE AND SCUBA DIVING: THE MEDITERRANEAN SEA

A few weeks ago I was discussing with a friend whether it is a good idea or not to recommend divers not to wear gloves as a measure for the safeguard of the environment, psychologically pushing on the potential risk of injuries caused my marine life forms if touched bare hands.

This gave me the idea for a short research about potential hazards that can be caused by marine life forms, focusing in particular on the Mediterranean area.

My purpose here is to show you how limited is the risks for us scuba divers, if we follow two simple rules:

• do not touch anything (also with the help of some buoyancy practice);
• respect marine life forms without harassing them.

In fact, statistically the high majority of accidents and injuries from marine life forms are caused by negligence or fault of scuba divers that provoke the animals!

Basically it is possible to identify 3 large categories of wounds that can be inflicted by marine life forms:

1. Traumatic injuries (e.g. bites and punctures);
   
   
2. Stinging and envenomation, often in connection with bites or punctures. Envenomation is the process by which a venom or toxin is injected into another being and can be active (like in the case of jellyfish and some cone snails) or passive (scorpionfish, weever);
   
   
3. Electrical shock: some marine animals can produce electricity through particular organs for hunting and self-defence purposes. 

Let us now have a look ath the most "dangerous" animals of the Mediterranean Sea. As you can easily realize, the danger is more in our head than real!

📸 (c) Dario Romeodario 

@romeopix.com

Jellyfish: there are over 100 different species of jellyfish. The stinging cells, called nematochysts, are located on the tentacles. Only in some species the venom causes an adverse reaction in humans, with effects that range form mild discomfort to extreme pain, but some species can be deadly. The contact usually occurs accidentally, with the diver not being aware of the presence of the jellyfish. Wearing a protection suit drastically reduces the risk of being stung.

📸 (c) Frédric Ducarme

Echinoderms: to this family belong sea urchins and starfish. Seaurchins in particular represent a hazard if involutarly touched by divers with bad buoyancy. Most species in fact possess long, sharp, pointed spines that are brittle and break off easily in contact with human skin and in some cases can be venomous. Divers and snorkelers can be injured while swimming on the surface in very shallow waters as well as when entering or exiting the water from shore dives.

 
Fireworms: fireworms can be found in the whole Mediterranean Sea, expecially around the Italian coasts. It is a slow creature, easy to be spotted crawling on the sea bottom, and is not considered a threat to humans unless touched. Its bristles can penetrate human skin, injecting a neurotoxin that produces intense irritation and a painful burning sensation around the area of contact. The sting can also lead to nausea and dizziness. This sensation lasts up to a few hours.

📸 (c) Roberto Pillon

Weever: weever do not have a swim bladder and during the day they bury themselves in sand snatching their prays. They have venomous spines on their dorsal fin and gills. The vast majority of injuries occur to the foot and are the result of stepping on buried fish. If stung, significant pain begins about 2–3 minutes after being stung. Weever stings cause severe pain: common and minor symptoms include, among others, severe pain, itching, swelling, heat, redness, numbness, tingling, nausea, vomiting, joint aches, headaches.

📸 (c) Wilfried Berns / Tiermotive.de

Scorpionfish: are a family that includes many of the world's most venomous species. In the mediterranean sea the most common species is the red scorpionfish. Normally 30 cm long, its colour ranges from red to light pink, with dark coloured blotches on the body. It is a sedentary demersal fish that lives on rocky, sandy or muddy bottoms. The spines, located on the dorsal fin and next to the gills, cause a very painful sting that can lead to loss of consciousness.

📸 (c) Steven van Tendeloo

Moray eels: there are aproximatively 200 species of moray eels worldwide. Altough their apperance may look aggressive as they are often seen with their mouth open, this is just their way to breathe. Moray eels are night hunters and feed on small fishes, molluscs such as squids and cuttlefish and crabs. They are generally not a threat if not molested, so as a general reccomandation, avoid sticking your fingers in their open mouth! Their bite is not venomous but can lead to infection.

📸 (c) Robert Patzner - Fishbase

Barracuda: although great barracuda can be potentially dangerous as some attacks agains humans have been recorded, this species is not present in the Mediterranean Sea. Here the only common species is the Sphyraena Viridensis, that has generally a length of 35 - 40 cm, can be spotted swimming in large groups and it is not aggressive. 

📸 (c) Gargolla

Stingrays: stingrays have a flat shape and can be usually found in shallow, sandy areas. They may be buried partially in the sand, making them more difficult to see. They have a stinger located on the tail. The stingray’s reaction to pressure on the body (as when a diver steps or kneels on the animal) is to whip the tail up and erect the spine so that this motion inflicts a puncture or a laceration wound. The initial symptom is pain, which can be significant and intensifies over several hours. It is common for stingray wounds to become infected.

📸 (c) Philippe Guillame

Electric rays: the electric-shock producing organs are located on the wings and the fish stuns its prey by hovering over it. If a diver accidentally touches the electric organs can receive a similar shock that can be painful but very unlikely to cause loss of consciousness. Most incidents occur in limited visibility when a diver is crawling on a sandy bottom.

📸 (c) Patrick Doll

Triggerfish: triggerfish have a strong- jawed mouth with teeth adapted for crushing shells that can cause painful injuries. Males are territorial and fierce in guarding their territories, that extends in a cone from the nest toward the surface, so swimming upwards can put a diver further into the fish territory. A horizontal swim away from the nest site is best when confronted by an angry triggerfish.

📸 (c) Doug Costa, NOAA / SBNMS

Sharks: Mediterranean Sea is home to about 90 species of sharks, most of them not dangerous for humans. Among them, spiny dogfish is provided with spines that secrete a mild venom, located near the dorsal fins. This species is not aggressive and uses its spines only defensively when captured.

Finally, just a few words about two invasive species that recently came to the Mediterranean area from the Red Sea through the Suez Channel (so called Lesseptian migration).

📸 (c) S. Rothman

Feathery stinging hydroid: common in the Red Sea, this species of hydroid has been spotted in the Mediterranean since the 90s. Hydroids are relatives of the jellyfish and also have nematocysts that may cause a mild stinging sensation. A more extensive contact results in a burning sensation. Victims generally develop pinpoint lesions, blotchy red rash, blisters and raised itchy weals, which may last up to 10 days before fading.

📸 (c) Alexander Vasenin

Lionfish: lionfish are venomous fishes commonly found in tropical reefs. Native to the Indo-Pacific, this fish is one of the most infamous invasive species in the Mediterranean. Lionfish have needlelike spines located along the dorsal, pelvic and anal fins. Their punctures can be extremely painful and lead to rapid development of localized edema and subcutaneous bleeding. Nevertheless, Lionfish are by no means aggressive. These fish are generally docile, allowing divers to approach closely. In fact, most lionfish-related incidents occur as a result of careless handling by spearfishing.