Animal
Smooth-head blobfish
The smooth-head blobfish lives deep in the sea near Australia. Down there it looks like a normal fish with a big head. It only looks like a soft blob when it is brought up out of the water.
The smooth-head blobfish lives on the deep sea floor off southern Australia, 600 to 1,200 meters down, where the water pushes in hard from every side. Its body is soft, with loose skin and no scales. In the deep, the water pressure helps hold it in shape, so it looks like a fish. Pulled up to the surface, that pressure is gone and its body sags, which is why photos look so 'blobby'.
Psychrolutes marcidus is a fathead sculpin (family Psychrolutidae) endemic to the continental slope of southern and eastern Australia at 600 to 1,200 meters. Its soft, scaleless body lacks a swim bladder; the familiar sagging shape is an artifact of depressurization when it is hauled up. It is occasionally taken as trawl bycatch and has not been evaluated by the IUCN.
Meet the smooth-head blobfish
The smooth-head blobfish is a deep-sea fish.
It has a big, round head and a body that gets thinner toward the tail. Its skin is soft and loose, pale brown or gray.
The smooth-head blobfish is a fish of the deep sea floor. It has a large, round head, a wide body that tapers toward the tail, big side fins and a large mouth. Its skin is smooth, loose and flabby, with no scales, and it is pale brown to gray.
It grows to about 30 centimeters long. You may have seen photos where it looks like a droopy pink blob, but that is not how it looks at home in the deep. Its shape changes when it is pulled up to the surface.
Psychrolutes marcidus is a ray-finned fish (class Actinopterygii) in the fathead sculpin family, Psychrolutidae. Fishes of Australia describes a very broad body, depressed in front and tapering behind, a large, globose head (about 40 percent of standard length), a large mouth with bands of fine teeth, big, angular pectoral fins, and smooth, scaleless, loose, flabby skin, uniformly pale brown to gray.
The dorsal fins are enclosed in thick, fleshy skin and look like one fin. FishBase gives a maximum length of 30 centimeters. The species name comes from Latin marcidus, 'withered' or 'weak', possibly because loose skin almost hides the features beneath it (Fishes of Australia).
Did you know?
Its name means 'weak' or 'withered'.
The name marcidus is Latin for withered or weak, probably because loose skin hides its body shape.
Latin marcidus means withered, wasted or weak, possibly referring to loose, flabby skin concealing the features beneath (Fishes of Australia).
The deep slope off Australia
Blobfish live near Australia, far down on the sea floor.
It is dark and cold there, and the water is very heavy.
The smooth-head blobfish lives only off Australia. It is found along the deep sea floor of the continental slope, from off southern Queensland, down the coast of New South Wales and around Tasmania, to the Great Australian Bight.
It lives 600 to 1,200 meters deep. Down there, the weight of all the water above presses in very hard. National Geographic notes that at about 1,000 meters the pressure is about a hundred times stronger than on land.
FishBase describes it as endemic to Australia, a temperate, bathydemersal (deep, bottom-living) species of the continental slope at 600 to 1,200 meters. Fishes of Australia gives a range from east-northeast of Coolangatta, Queensland, to south-southwest of Eucla, Western Australia, including off Tasmania.
The Beaty Biodiversity Museum describes it as living at least 600 meters deep, where pressure is intense. National Geographic notes that at about 1,000 meters the pressure is roughly a hundred times that at the surface, that no sunlight remains below about 1,000 meters, and that average temperatures there are about 4 °C (39 °F).
Continent
Its habitat
Where can you find this animal?
- Lives here naturally · Countries and seas named by a scientific source
- Sightings recorded · Records of wild sightings (GBIF)
Lives here naturally · Countries and seas named by a scientific source
Endemic to Australia: the deep continental slope (600 to 1,200 meters) from off southern Queensland and New South Wales to Tasmania and the Great Australian Bight. Australia is shaded whole, but the fish lives only on the deep sea floor off its southern and eastern coasts.
Places: Australia.
Source: https://www.fishbase.se/summary/Psychrolutes-marcidus.html · checked October 2026
Sightings recorded · Records of wild sightings (GBIF)
Counts of GBIF records of wild observations (human and machine) and preserved specimens. Records include introduced populations, vagrants, escaped or released animals and misidentifications, so a country with records is not necessarily part of the native range.
Wild sightings have been recorded in Australia, New Zealand, Pacific Ocean, Indian Ocean, Southern Ocean, Arctic Ocean and Atlantic Ocean.
Source: gbif · checked October 2026
Range maps show where scientists say an animal lives, often country by country. An animal may live in only part of a country shown, and sightings records can include animals that wandered far from home.
Waiting on the sea floor
Blobfish do not chase their food.
They stay near the sea floor and eat small animals that come by.
Scientists know little about what the smooth-head blobfish eats. National Geographic describes blobfish as 'lie-in-wait' predators: they stay near the sea floor and eat what passes by, such as crustaceans, brittle stars and sea anemones, and even dead animals that sink down.
The smooth-head blobfish has a large mouth with bands of tiny teeth in both jaws.
Species-specific diet studies were not found in the sources used. National Geographic describes blobfish in general as lie-in-wait predators that eat crustaceans, brittle stars, anemones and carrion, which saves energy where food is scarce; it is not clear which species these observations come from.
Anatomically, P. marcidus has a large mouth reaching to below the rear of the eyes, a broad band of villiform (fine, brush-like) teeth in both jaws and no teeth on the roof of the mouth (Fishes of Australia).
Did you know?
Blobfish can float just above the sea floor.
A jelly-like layer makes the blobfish a little lighter than water, so it can hover just above the sea floor.
High water and fat content make blobfish slightly less dense than seawater, letting them bob along the seabed (National Geographic).
Why it looks 'blobby'
In the deep sea, the blobfish looks like a normal fish.
Its soft body is held in shape by the heavy water around it. When it is brought up, its body goes soft and droopy.
A blobfish's body is built for deep water. It has no swim bladder, the air-filled bag many fish use to float, which would be squashed at that depth. Its body is soft, with a lot of water and fat and a thick, jelly-like layer under the skin.
In the deep, the water pressure helps hold this soft body in shape, and the blobfish looks like a regular fish. When it is pulled up in a net, the pressure drops quickly, the body is damaged and it sags into the droopy shape seen in famous photos.
The Beaty Biodiversity Museum explains that the species copes with intense pressure by lacking a gas bladder and having soft, rubbery skin, and that it only looks distorted when brought up to sea-level pressure. National Geographic adds that blobfish lack strong bones and thick muscle, rely on water pressure to hold their shape, and have a high water and fat content with a jelly-like layer that makes them slightly less dense than seawater, so they can hover just above the seabed.
According to National Geographic, the sagging shape seen in photographs results from tissue damage during rapid depressurization as the fish is hauled up.
Still a mystery
Nobody knows much about baby blobfish.
They live so deep that scientists hardly ever see them.
Scientists know very little about how smooth-head blobfish grow up, because they live so deep and are rarely seen alive.
National Geographic reports that researchers believe blobfish in general lay large clutches of eggs in nests, with a parent staying close to tend them. It is not yet known whether this is true for the smooth-head blobfish.
No species-specific information on reproduction, growth or lifespan was found in the sources used. National Geographic reports, for blobfish as a group, that researchers believe they reproduce in groups, laying clutches of around 100,000 eggs per nest that a parent tends; these observations may come from other Psychrolutes species.
The gap is typical of deep-sea fishes: most of what is known comes from specimens caught in trawls (National Geographic), which reveal anatomy but little about behavior or life history.
A slow, energy-saving life
Blobfish move slowly.
They float just above the sea floor and save their energy.
Because its body is a little lighter than the water around it, a blobfish can hover just above the sea floor without swimming hard. National Geographic says this lets it bob along the seabed and save energy.
What smooth-head blobfish do each day is still mostly unknown, because almost all of them have been seen only after being caught in nets.
The jelly-like flesh makes blobfish slightly less dense than water, allowing them to float just above the seabed (National Geographic), an energy-saving lifestyle in a food-poor habitat according to the same source.
Observations of living P. marcidus are scarce; most specimens are trawl bycatch (Fishes of Australia), so its behavior is inferred largely from its anatomy and from related blobfishes.
Did you know?
At home in the deep sea, a blobfish looks like a normal fish.
Underwater at its own depth, a blobfish has a regular fish shape. It only looks droopy when it is brought to the surface.
At depth it looks 'quite normal'; the distortion appears only at sea-level pressure (Beaty Biodiversity Museum).
Caught by accident
Sometimes blobfish get caught by accident in fishing nets.
Scientists want to learn more about them so they can help.
The smooth-head blobfish has not been checked by the IUCN, so its conservation status is unknown. It is not fished on purpose, but it is sometimes caught by accident in nets dragged along the deep sea floor.
National Geographic notes that bottom trawling and warming oceans may threaten blobfish. Learning more about deep-sea animals helps people protect them.
The IUCN lists Psychrolutes marcidus as Not Evaluated (FishBase, citing Red List version 2025-2), so its status is unknown. Fishes of Australia notes it is occasionally taken as bycatch in commercial trawls.
National Geographic suggests that deep-sea fishing and bottom trawling, which drags weighted nets along the seafloor, and warming oceans may threaten blobfish; it reports no known natural predators. Population size and trends are not known.
Did you know?
Blobfish have no swim bladder.
Many fish float using an air-filled bag called a swim bladder. Blobfish do not have one.
Lacking a gas bladder avoids a compressible air space at depth (Beaty Biodiversity Museum; National Geographic).
Amazing facts
-
At home in the deep sea, a blobfish looks like a normal fish.
Underwater at its own depth, a blobfish has a regular fish shape. It only looks droopy when it is brought to the surface.
At depth it looks 'quite normal'; the distortion appears only at sea-level pressure (Beaty Biodiversity Museum).
-
Blobfish have no swim bladder.
Many fish float using an air-filled bag called a swim bladder. Blobfish do not have one.
Lacking a gas bladder avoids a compressible air space at depth (Beaty Biodiversity Museum; National Geographic).
-
Its name means 'weak' or 'withered'.
The name marcidus is Latin for withered or weak, probably because loose skin hides its body shape.
Latin marcidus means withered, wasted or weak, possibly referring to loose, flabby skin concealing the features beneath (Fishes of Australia).
-
Blobfish can float just above the sea floor.
A jelly-like layer makes the blobfish a little lighter than water, so it can hover just above the sea floor.
High water and fat content make blobfish slightly less dense than seawater, letting them bob along the seabed (National Geographic).
Words to know
- pressure
- how hard something pushes on a surface; deep water pushes very hard
- swim bladder
- an air-filled bag inside many fish that helps them float
- deep sea
- the dark, cold part of the ocean far below the surface
- endemic
- found naturally in only one place in the world
- bycatch
- animals caught by accident when people are fishing for something else
- continental slope
- the steep sea floor that drops from the shallow edge of a continent into the deep ocean
Discovery challenge
-
Why does a blobfish look droopy in photos?
Why do photos of blobfish show a droopy blob?
What causes the blobfish's slumped appearance in photographs?
- It was pulled up from deep water
- It is always that shape
- It is very sleepy
Show the answer
It was pulled up from deep water
It came up from the deep sea, where heavy water held it in shape.
Out of the deep, the pressure is gone and its soft body sags. At home it looks like a fish.
Rapid depressurization during capture damages the soft tissues, causing the slumped shape.
-
Where do smooth-head blobfish live?
Where does the smooth-head blobfish live?
What is the range of Psychrolutes marcidus?
- Deep in the sea near Australia
- In lakes in Africa
- On coral reefs near the surface
Show the answer
Deep in the sea near Australia
They live deep in the sea near Australia.
They live on the deep sea floor off southern and eastern Australia, 600 to 1,200 meters down.
Endemic to Australia's continental slope, Coolangatta to Eucla, including Tasmania.
-
What does a blobfish NOT have?
Which body part do blobfish not have?
Which structure is absent in blobfish?
- A mouth
- A swim bladder
- Fins
Show the answer
A swim bladder
It has no swim bladder, the air bag many fish have.
It has no swim bladder, the air-filled bag many fish use to float.
There is no gas (swim) bladder, which would be compressed at depth.
-
What does the deep water do for the blobfish's body?
How does deep-sea water pressure help the blobfish?
What role does ambient pressure play for the blobfish's body?
- It helps hold its soft body in shape
- It makes the blobfish glow
- It keeps the blobfish warm
Show the answer
It helps hold its soft body in shape
The heavy water helps hold its soft body in shape.
The pressure helps its soft body keep a normal fish shape.
Lacking strong bones and muscle, the body relies on ambient pressure to hold its shape (National Geographic).
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For parents & teachers
What children will learn
- Explain how water pressure increases with depth and how the blobfish's body suits high pressure.
- Understand why the famous droopy photos do not show what the blobfish looks like at home.
- Recognize that much about deep-sea animals is still unknown.
Recommended ages: 3 to 17 · About 10 minutes
Talk about it
- Why might an animal look very different when it is taken out of its home?
- Why is it unfair to judge an animal by a single photo?
- How could scientists study deep-sea fish without bringing them to the surface?
Try at home or in class
- Push a sealed, half-full water bottle into a deep sink or tub and feel the water push back; deeper water pushes harder.
- Squeeze a water balloon gently in a bowl of water and then in the air to see how surrounding water supports a soft shape.
Key vocabulary: pressure, swim bladder, deep sea, endemic, bycatch, continental slope
Where these facts come from
- GBIF Backbone Taxonomy and GBIF Occurrence Search , Global Biodiversity Information Facility (CC0 1.0 (backbone); occurrence counts are facts derived from records under CC0, CC BY and CC BY-NC)
- Smooth-head Blobfish, Psychrolutes marcidus , Fishes of Australia (Museums Victoria)
- Psychrolutes marcidus, Smooth-head blobfish: species summary , FishBase
- Beauty is in the eye of the beholder? , Beaty Biodiversity Museum, University of British Columbia
- Blobfish , National Geographic
- Wikidata , Wikimedia Foundation (CC0 1.0)
Checked, not yet human-reviewed. Last updated October 27, 2026. Spotted a mistake? Tell us.