Who?
Family: Diodontidae
pecies: Diodon hystrix
Species ID: D.DHb
Description: A fish with large eyes (1), a wide flattened mouth (2), and large, rounded fins. This species has a uniformly dull brown to green back, with a pale mouth and belly, and is covered in small dark spots extending onto the fins (3). The short, sharp spines (4) characteristic of the porcupinefish, lie flat against its body, standing on end only during inflation. Sexes appear similar and juveniles resemble adults
Maximum size: 91 cm (36 in)
Longevity: At least 10 years, possibly up to 15
Status: Not currently on the IUCN endangered species list
Porcupinefish & People: Given its toxic nature, this species is not caught for food. It is however, occasionally fished for public aquaria and as a curiosity souvenir
Where?
Geographical Range: Occasional to common in shallow reef areas throughout the worlds tropical seas
Coral Reef Zone: Porcupinefish are found in the back reef, fore-reef and drop-off zones
Favourite Habitat: Porcupinefish prefer structurally complex reefs, with plenty of holes and caves to hide in
Depth Range: 2–50 m (7–160 ft)
A Day in The Life
Dawn: Nocturnal feeding declines and fish find shelter for the day
Day: Porcupinefish hide in shallow caves or under ledges
Dusk: Porcupinefish emerge from shelters to forage. Spawning may also occur
Night: Porcupinefish actively forage for small crustaceans
Who Eats Who?
The porcupinefish feeds mainly on hard-shelled invertebrates like shrimp, crabs, urchins, snails and clams. As an adult, the porcupinefish has few natural predators due to its large size, toxicity, and ability to inflate. Juveniles, however, are preyed upon by a variety of large predators in the open ocean including dolphinfish, wahoo, and marlin.
Scuba Diver & Snorkeler Best Practices
Don’t disturb the wildlife. Porcupinefish may inflate if harassed. It is important to realize that although inflation is a natural antipredator response, it is extremely stressful for the fish, requiring a great deal of energy and rendering the fish immobile until it can deflate. Under no circumstances should inflation be provoked on purpose. Always remember that you should never touch or otherwise interfere with marine life – remember the maxim: “Take only photographs and leave only bubbles.”
What?
Approach
These fish are wary of divers and snorkelers, and often retreat to shelters if they approach too closely, stay at a distance to observe these fish without disturbing their normal behaviour.
Feeding Behaviour Porcupinefish are nocturnal, carnivorous predators specialized in eating hard-shelled prey. Their strong beak-like mouth is used to seize and crush prey such as urchins, crabs, snails and clams. Like many animals that eat hard or prickly prey, porcupinefish also posess thick, rubbery lips to protect them from being injured by the spines and broken shells of the prey they eat. At night, porcupinefish can be observed actively combing the reef for food and investigating sandy areas, crevices and caves where their prey might be found.
Observe, record & share:
O D.DHb-101 – Digging: Porcupinefish sometimes blow jets of water into the sand to uncover burrowing prey such as crabs, snails and clams
O D.DHb-102 – Hard-shelled prey: Porcupinefish crush hard-shelled prey with their strong jaws and feed on the soft tissue inside
Attack & Defense Behaviour Porcupinefish are generally shy, do not defend territories, and will attempt to escape to shelter at the first sign of a threat. Their relatively large size and toxicity make them difficult to stomach for most reef predators. Occasionally, porcupinefish become aggressive and chase other members of their species - perhaps to defend mates or food resources. When chased, a porcupinefish displays a series of large, dark blotches on its back to show that it is submissive and does not want to fight. Porcupinefish also possess the amazing ability to inflate up to three times their normal size by rapidly swallowing a large volume of water. Inflation also causes the body spines to stand on end, making this species a much less appetizing snack.
Observe, record & share:
O D.DHb-201 – Hiding: Wary porcupinefish seek shelter in caves, where they peek out at divers
O D.DHb-202 – Chase: One porcupinefish chases another
O D.DHb-203 – Submissive pattern: A pattern of dark blotches on the back indicates submission
O D.DHb-204 -– Inflation: A porcupinefish under extreme stress will raise its spines as it inflates to several times its original size, making it too big and prickly for most predators to swallow
Reproductive Behaviour Although porcupinefish spawning behaviour is not well described, it is likely to be similar to that of its close relative the balloonfish (Diodon holocanthus), which has been well studied. Soon after dusk, males search for ripe females and court them by nuzzling and nudging their belly. The female is pushed towards the surface by the male where both sexes release their eggs and sperm simultaneously before returning to the reef. Spawning is thought to occur year round in porcupinefish, but activity peaks between the months of February and March.
Observe, record & share:
O D.DHb-301 – Ripe female: Females that are ready to spawn appear swollen with eggs
O D.DHb-302 – Male courtship: One or several males follow and nuzzle a ripe female
O D.DHb-303 – Spawning rise: One or several males nudge the belly of a ripe female, pushing her towards the surface
O D.DHb-304 – Surface spawning: Males and females release a cloud of eggs and sperm near the surface before returning to the reef
Highlight Behaviours
Inflation: In order to inflate, porcupinefish are able to pump large amounts of water into their stomachs (1) while their highly flexible tissues and skeleton can stretch to allow the expansion. When inflated, the spines of the porcupinefish are made to stand on end and the fish can reach up to three times its original size (2). Once the threat has passed, the porcupinefish simply spits out the water it has swallowed to return to their original size. If a porcupinefish accidentally inflates by swallowing air, for example when brought to the surface by a fishing line or by aquarium specimen collectors, deflation becomes much more difficult and the fish often die.
Did You Know?
• Like many other pufferfish, including the infamous Japanese fugu, the porcupinefish produces a poison called tetrodotoxin, which is one of the most toxic natural substances known to science. When ingested, it progressively shuts down the nervous system and can cause paralysis and death within hours.
• Porcupinefish tetrodotoxin was long ago a key ingredient used by Haitian voodoo shamans in a potion used to put the victim into a deep coma, so they were believed dead. After burial, shamans would rescue and revive the victim with a partial antidote, made of plants causing amnesia and hallucination, allowing the shaman to gain control over the confused victim and force them into labour as slaves. From this remarkable ritual, called zombification, we have obtained the modern Hollywood zombie!
What to do?
Share your observations today! Discover your species of interest, observe its behaviour, and share your pictures and videos with friends and coral reef enthusiasts around the world! Upload media to the web, tagged with species common name (ex.: trumpetfish) and species ID code (ex.: A.AM) or species behaviour code (ex.: A.AM-101)
Observation Key
O Easy
O Not so easy
O Tough
