Introduction
The ocean
conceals some of nature's most fantastic creatures, and the Japanese
angel shark (Squatina japonica) is certainly one of them. Pleated like a ray,
this extraordinary shark species is well camouflaged against sandy ocean beds,
lie in wait to pounce on unwary marine prey. The Japanese angel shark, found
both by beginners and experienced marine life observers, gives a fascinating
look at the nature of ocean life beneath the waves.
In the article
below, we explore the biology, behavior, and importance to the ecosystem of,
and threats to, this remarkable fish.
What Is the Japanese Angel Shark?
DescriptionThe Japanese angel
shark is a benthic species concentrated in the northwestern Pacific Ocean along
the coasts of Japan and Korea, and also in the East China Sea. It is a member
of the Squatinidae family (or “angel sharks”) which have uniquely temperate or
tropical marine species with flattened bodies and greatly enlarged pectoral
fins that give the impression they are flying through water.
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Physical Characteristics: Camouflage at Its Best
With its adaptations, the
Japanese angel shark is a specialized ambush predator.
Key Features
• Flat, wing-like body: The shape
of the body allows this shark to lie almost flush with the ocean floor.
• Mottled skin patterns: The
patterns serve to camouflage the fish and keep the shark hidden.
Wide mouth and sharp teeth: Ideal
for capturing fast-moving prey.
Small dorsal fins near the tail:
In contrast with many other sharks, its dorsal fins are situated unusually far
towards the back.
These features enable the angel
shark to burrow in sediment, leaving only its eyes and a portion of its head
exposed.
Habitat: Where is the Japanese Angel Shark found?
This species occurs in the
temperate waters of the coast at depths of 10 to 300 m, commonly. You’ll see
it:
• On sandy seabeds sleeping
• In seagrass meadows as
camouflaged resting places
• Around coral reefs and rocky
bottoms
It is distributed through the Sea
of Japan, East China Sea to the coasts of major islands of Japan. The sand
tiger prefers areas where the bottom is soft enough to burrow its snout in, yet
teeming with fish.
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Diet and Hunting Behavior
The hunting of the Japanese angel
shark is considered one of the most interesting ways sharks can catch their
prey.
Ambush Strategy - Predator
• It lies buried in the sand,
motionless.
• When a fish or crustacean comes
within range, they lunge up at blinding speed.
• The strike lasts just a second,
and nothing can escape from it.
Typical Diet
• fish
• squid
• small sharks
• crabs
• mollusks
This animal is unique among
sharks in that it depends heavily on stealth rather than pursuit.
Mating Behavior
The Japanese angel shark is
ovoviviparous, with embryos encased in eggs that remain within the mother's
body until the young are born.
Main factors of reproduction
• The pregnancy duration is 9–12
months.
• Females give birth to a litter
of 7-15 pups.
• They are fully formed miniature
sharks, and can hunt straight away.
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Conservation status: What is threatening the species?
The Japanese angel shark is
classified as Endangered on the basis of conservation assessments due to:
1. Overfishing
They are also frequently snagged
as bycatch in fisheries that use trawls and gillnets.
2. Slow Reproduction
The population is not able to
bounce back quickly with long pregnancy terms and small numbers of young.
3. Habitat Degradation
The development along the
coastlines and pollution of the seas are also disturbing their habitats.
HYDROPLEURAEPLEURAELEUS
4. Use by Humans
In certain areas the Angel Sharks
are sponsored for their meat or used in traditional recipes.
Conservation organizations
stress the importance of stringent fishing control measures and protection of
habitat to stop any further degradation.
Environmental importance
Broadly Overlooked, the
Japanese angelshark, Squatina japonica, is an important indicator for the
marineecosystem health.
Contributions
• Regulates fish
and crustaceans population
• Contributes
to a balanced food web
• When
hunting, it ter- races the seabed, which contributes to sediment health
The protection of this species is
an allowance for a larger benefit to the ocean ecosystem.
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External Resources for Further Learning
(Plain-text URLs provided
for Google safety)
• IUCN Red List – Japanese
Angel Shark
https://www.iucnredlist.org
• National Oceanic
and Atmospheric Administration (NOAA)
https://www.noaa.gov
• Japan Agency for Marine-Earth
Science and Technology (JAMSTEC) https://www.jamste c.go jp
• Monterey Bay Aquarium: Species
Guides
https://www.montereybayaquarium.org
These reliable references contain
in-depth information about the science and research.
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