Can a Cookiecutter Shark Bite a Submarine?
The short answer
Yes. In the 1970s, cookiecutter sharks about 50 cm (20 inches) long bit the rubber sonar domes of US Navy submarines. The oil inside, which carries the sound, leaked out, and several subs had to go back to base for repairs. The fix was fiberglass covers around the domes.
The shark lives by cutting round plugs of flesh out of animals much bigger than itself. The rubber dome got the same bite.
Lips, a saw and a twist
The cookiecutter seals its lips onto its prey like a suction cup. Its pointed upper teeth hold on while a saw of big, serrated bottom teeth cuts in. Then it twists its whole body around the bite and swims off with a round plug of flesh. The largest crater wounds Everet Jones described in 1971 measured 4 or 5 cm by 7 cm.
Jones tested the idea in 1969 on a research ship in the Pacific. He took a nectarine from the ship's galley, pushed a dead cookiecutter's teeth into it, turned the shark around the bite and got the same round crater found on whales.
The scars turn up on sperm whales, dolphins, tuna and seals. In 2013, scientists described a photo of a great white, taken by a diver in a shark cage near Guadalupe Island, Mexico. It had a cookiecutter bite near its mouth. The cookiecutter's bottom teeth fall out a whole row at a time, and it swallows them. The next row is already standing up behind.
A glowing belly and a dark collar
By day the cookiecutter lives below 1,000 m (3,281 ft). At night it rises to the surface to feed. Its belly glows an even green. Seen from below, that glow blends into the dim light coming down from the sky, so the shark's outline nearly vanishes. The glow reportedly lasts up to three hours after the shark dies.
Only the dark brown collar around the throat breaks the glow. In 1998 the scientist Edith Widder suggested that, from below, this patch looks like the kind of little fish a tuna hunts. If she is right, the hunter swims in for a snack and becomes the snack. The idea is still a hypothesis.
Where the Navy story comes from
The submarine account is traced to a 1978 article by C. S. Johnson in the US Naval Institute's Proceedings. The Florida Museum also notes reports of this shark leaving crater marks on the sonar domes of nuclear submarines. At first nobody knew what was biting the subs, and an enemy weapon was one fear. The bites meant repairs. No source we found says a shark did a submarine more harm than that.
Key numbers
| What | Number | Source |
|---|---|---|
| Largest size of a female cookiecutter shark | 56 cm (22 in) | Florida Museum of Natural History, Cookiecutter shark profile |
| Largest size of a male cookiecutter shark | 42 cm (16.5 in) | Florida Museum of Natural History, Cookiecutter shark profile |
| Length the film gives the shark | about 50 cm (20 in) | Our arithmetic from Florida Museum of Natural History, Cookiecutter shark profile |
| When the sharks bit Navy sonar domes | the 1970s | Johnson 1978, US Naval Institute Proceedings |
| Largest crater wounds described | 4 or 5 cm by 7 cm | Jones 1971, Fishery Bulletin |
| Year of the nectarine test on a research ship | 1969 | Jones 1971, Fishery Bulletin |
| Where it lives by day | below 1,000 m (3,281 ft), rising to the surface at night | Florida Museum of Natural History, Cookiecutter shark profile |
| How long the glow lasts after the shark dies | up to 3 hours (reported) | Florida Museum of Natural History, Cookiecutter shark profile |
| Year the dark collar was proposed as a lure | 1998 | Science News 1998 |
| Year a bite on a great white was reported | 2013 | Pacific Science, 2013 |
What the film simplifies
- The film's name card says 20 inches. Females reach 56 cm (22 in) and males 42 cm (16.5 in), so a 20 inch shark is a big female.
- In the close shots the shark is drawn far too big next to the submarine. In the wide shot she is only a glowing speck on the sub's tower, which is closer to her real size.
- The sub's "ear" is drawn as a dome on top of its tower. The film never says where the dome sat, and no source we found does either.
- The sources say an enemy weapon was one early fear, but none says who feared it. The admiral, the war room and the robot octopus poster are cartoon.
- The bite is drawn as one clean twist by the shark alone. The scientists who studied it think the moving prey and the drag of the water help turn the shark around the bite.
- The whale's "Every. Single. Night." is a joke. The shark does feed at night, but no source says one whale gets bitten every night. The talking submarine, shark, whale and tuna are cartoon.
At a glance
Runtime 1 minute 5 seconds · Topics: Ocean life, Sharks, Camouflage and light, Submarines · Captions on YouTube · Full script below
Test yourself
How does a cookiecutter shark take a round bite out of an animal far bigger than itself?
Answer
It seals its lips on like a suction cup, cuts in with a saw of big bottom teeth, then twists its whole body around the bite and pulls out a round plug.
The cookiecutter's belly glows. Why would glowing make it harder for a tuna swimming below to see it?
Answer
From below, the green glow blends into the dim light coming down from the sky, so the shark's outline nearly vanishes. Only the dark collar shows, and one scientist thinks it looks like a little fish.
The largest female cookiecutters reach 56 cm and the largest males 42 cm. How much longer is the female, and by roughly what fraction?
Answer
14 cm longer, which is about a third longer than the male.
The script
The Sub: Get it off! Get it off my ear!
Cookiecutter: Rubbery.
Host: Yes, really. In the 1970s, the cookiecutter shark bit US Navy submarines.
Host: The best thief in the sea.
Cookiecutter: Thief? I take samples.
Cookiecutter: Step one. Suction cup.
Cookiecutter: Step two. The saw.
Cookiecutter: Step three. The twist!
Whale: Every. Single. Night.
Host: That's the cookie in cookiecutter.
Host: Dolphins, tuna, seals... even great whites.
The Sub: And me!
Host: Most thieves wear black.
Cookiecutter: I wear the lights.
Host: From below, her glowing belly blends into the light above.
Host: All but her dark collar, which may look like a little fish.
Tuna: Ooh, snack!
Tuna: I'm the snack!
Cookiecutter: And then... the big one.
The Sub: Nothing gets past my ears.
Host: His ear was a rubber sonar dome, full of oil that carries the sound.
The Sub: What?
Admiral: Gentlemen. Could it be a secret enemy weapon?
Cookiecutter: Surprise.
Host: The fix? Fiberglass covers.
The Sub: Nothing gets past my ears.
Cookiecutter: Fine. Back to whales.
Whale: Oh, so I'm the backup?
Sources
- Females reach 22 inches (56 cm) and males 16.5 inches (42 cm); the lips and upper teeth latch on and the shark spins its body to remove a cookie shaped plug with its serrated lower teeth; an even green glow reported to last up to three hours after death; below 1,000 m by day, rising to surface waters at night to feed; lower teeth shed and swallowed; a dark brown collar around the gill region; seals, whales and dolphins among its prey; crater marks on the sonar domes of nuclear submarines.Florida Museum of Natural History, Cookiecutter shark profile
- Crater wounds on whales, dolphins and tuna; the lips form a vacuum on a smooth surface; the largest wounds 4 or 5 cm by 7 cm; the 1969 nectarine test; water drag turning the shark around the bite; the lower teeth shed as a unit with the next row already erect (citing Strasburg 1963).Jones 1971, Fishery Bulletin
- Cookiecutter sharks bit the rubber sonar domes of US Navy submarines in the 1970s, the sound carrying oil leaked, subs went back for repairs, and fiberglass covers fixed it.Johnson 1978, US Naval Institute Proceedings
- An attack by a cookiecutter shark on a white shark, reported in 2013.Pacific Science, 2013
- A bite wound near a white shark's mouth, photographed by a diver in a shark cage near Guadalupe Island; the study appeared in Pacific Science in January 2013.Florida Museum news, 2013
- Seen from beneath, the shark's glow blends in with dim light from the sky; Edith Widder suggests the dark chin patch looks like a little fish a predator such as a tuna hunts; the prey's motion helps the teeth scoop around like a melon baller.Science News 1998