Despite their name, cuttlefish (also known as cuttles) are not fish. They are invertebrates and close relative to the octopus, squid, and nautilus. Those animals are the sea’s expert camouflagers and are among the most clever animals on the planet. You’ll be astounded when you learn more about the incredible cuttlefish facts listed below!
1. Cuttlefish is the king of camouflage
Despite being colorblind, this creature is an expert at concealment. Cuttlefish camouflage in a variety of ways, including changing their color, pattern, texture, and even shape to imitate anything in their surroundings.
– They can change color to blend in with their environments
There’s a reason why they call cuttlefish the chameleon of the sea. They can change the color of their skin in less than one second to match their surroundings. They can even change the color to every colorful rock and coral they swim by.
And if that doesn’t impress you enough, check this out! The color they change is not only still but also moving. To do this, cuttles change color in fast rhythms, giving the illusion that there are color waves rolling across their bodies.
The attractive light show is a method of helping cuttles in catching prey.
So how do cuttlefish change colors? Cuttlefish skin has chromatophores which are pigment-producing cells and leucophores which are light-reflecting cells. And every square millimeter of the cuttlefish’s skin, there are about 200 of these cells.
Being closest to the surface is yellow pigment cells, followed by the red and the orange, then brown and black pigment cells, and finally the green and the blue (iridophores).
The pigment cells are surrounded by microscopic bands of muscle. And cuttles regulate the contraction of these muscles independently through brain signals, resulting in a specific hue on a specific area of the skin. Depending on how much these muscles flex and how much light the leucophores reflect, different levels of pigment will appear.
A cuttlefish’s color may indicate its emotion. If the cuttlefish unexpectedly changes to black, it may feel furious, or frightening. They are trying to create a menacing image to scare away suspected predators. If it wants to tell a full story to other cuttles, it will show a simple color sequence.
– They can imitate objects in their environment
Cuttles may mimic the shape and texture of things around them in order to avoid predators. Their cousin octopus can do this too. Cuttles alter their texture by stretching or contracting microscopic bumps on their bodies called papillae, which allows them to better match the lumpy pebbles, sand, or other surfaces where they’re blending in.
To frighten off predators and catch more fish, the Pharaoh cuttlefish may transform into something mimicking a hermit crab. The others will utilize their camouflage to creep up on prey. By pretending to be a rock here or a piece of seaweed there, cuttles slowly approach the unfortunate prey (crab or fish) and quickly seize the prey with their two feeding tentacles and swallow it.
Some dive into the sand and burrow beneath their victim, while others camouflage into the water and attack from above. Because each cuttlefish species has a unique hunting technique, they will use a variety of tactics.
You may read some of the other Camouflage animal articles for further information:
2. They have three hearts
Green-blue blood is one of the odd features of cuttles. This is because the species use hemocyanin which includes copper to carry oxygen through the bloodstream, not protein hemoglobin. Compared to hemoglobin, hemocyanin transports far less oxygen. That’s why cuttles need to pump blood through the bloodstream rapidly and they need 3 distinct hearts to do this.
Among 3 hearts, two of them have duties to pump blood to their huge gills, while the left one circulates oxygenated blood throughout the remainder of its body. Unlike other mollusks, cuttlefish have a closed circulatory system, yet it is similar to cephalopods and vertebrates.
3. Cuttlefish are extraordinarily intelligent
Over 400 million years ago, cuttlefish, squid, and octopuses evolved and they are the most intelligent invertebrates. The brain-to-body ratio of cuttlefish is the highest of any creature. They are put through obstacle courses and other trials in marine biology labs to measure their intelligence.
– They can count
Cuttles definitely shine when counting shrimps. According to a study, one-month-old cuttlefish can distinguish between a box with 5 shrimps and a box containing 4 shrimps. However, cuttles took more time to determine which box to eat from when the boxes had more shrimps. And this is a base for researchers to assume that cuttles literally count the shrimp number before deciding.
Researchers came to an end that the cuttlefish’s ability to compare numbers is equal to that of rhesus macaques and 12-month-old human babies.
– They are dexterous
Cuttlefish have tentacles that can toss rocks around. To examine how agile cuttles can be, they put a shrimp in a glass jar and check if the cuttles can open it or not. As expected, all the cutters not only accomplished, but many also use their tentacles to grab the top and twist it to open. Cuttles’ problem-solving ability is amazing!
Cuttles are extremely creative animals. They frequently take objects and items from their environments to use as tools for hunting or playing with. They use sticks to pull crabs from their shells! They even cooperate: one keeps the crab while another prises the shell open, and they all enjoy the meal.
– They’re good learners
Cuttlefish are good at spatial awareness, navigational ability, and notably observational learning. Cuttles are curious, gregarious animals as a result of their intelligence. They will come up to you if you notice them in the aquarium. They may even knock on the glass to attract your attention!
Cuttles can recall faces throughout their lives, and in captivity, they frequently swim over to welcome their favorite person.
– Cuttles can regulate their buoyancy
A cuttlefish is a type of cephalopod that is related to squids and they have ten tentacles. Like squids, they lost their hard outer shells. However, unlike squids, they have a large internal shell on the interior. The shell is cuttlebone and it is composed of the mineral aragonite. The cuttlebone enables them to adjust the liquid-to-gas ratio within their bodies, allowing them to float.
4. They have refined tastes
If you have a cuttlefish, you’ll know how smart and mischievous it is when feeding it. Cuttles have a whole plan on their mind to eat. Cuttles will eat fewer crabs earlier in the day if they know their favorite dish (shrimp) is served later.
In a study, cutters consistently fed shrimp in the evening and devoured fewer fish and crabs throughout the day. On the other hand, those who were fed shrimp at random times did not change their eating behaviors during the day.
Obviously, the cuttles make decisions depending on the expectation of something happening in the future. They have complex cognitive abilities.
5. Cuttlefish – Animal Puzzle
6. They have excellent vision
Do you know that cuttles are colorblind? However, this doesn’t affect their impressive vision. This species can still identify which colors and patterns to use when camouflaging, without any difficulties.
Although cuttles can’t see color, they perceive polarized light, giving them an advantage in spotting prey. Even before birth, cuttles may utilize their eyes to detect prey for hunting when it hatches.
The cuttlefish has dark crimson eyes that are huge in comparison to its body. Because the cuttlefish’s optic nerve is located behind the retina, these eyes are extraordinarily developed and have no blind spots.
With W-shaped pupils, cuttles can see in all directions, see a broader horizontal range, and can see almost entirely behind themselves by just moving their eyes. These pupils also help regulate the brightness level of light entering the eye.
Unlike us, cuttles don’t change the shape of their lens to concentrate on an object. Instead of that, they change the shape of their eyes.
7. Male cuttlefish can change gender
Yes, you heard it right! Male cuttlefish can alter their gender, but not in a literal sense.
To lure females in the breeding season, male cuttles will employ their color-changing skills. However, such flashy displays attract not only females but also other males. In a world where the number of males is far more than the females’, this is too risky. It’s like an alert to tell the other males that: Hey! there is a girl here, come and get it.
That’s why they need to use a gender-bending disguise technique. The male will put typical feminine designs on one side of his body while displaying usual male patterns on the other.
This gender-bending camouflage tricked other competitors into thinking they were only watching 2 girls hanging together. By utilizing this deceptive appearance, the male has more time to persuade the female to mate with them before the rival finds out.
Small male cuttles often use this trick when there is just one male opponent around.
In some cases, males will completely masquerade themselves as females to get past bigger males, sneak in and mate with the female To do this, the male has to change his hue and conceal his fourth pair of arms (females only have three), and posture himself as if he is pregnant or he’s not in the mood to mate.
According to researchers, both males and females have their own standards when choosing partners.
– Females won’t look for males if they’ve just had mated. To let the males know about this, they will exhibit a white stripe over their body. However, most males don’t get the message.
If the females are alone for a while, they will lower their criteria and apply a receptive position for any passing male.
– Male cuttlefish are different. They display a high predilection for unknown females. They also hover optimistically near females who hadn’t recently mated
8. Twisted mating procedure
Cuttlefish, like most cephalopods, reproduce only once in their life. Their breeding season is often in the spring and summer (from March to June). Cuttles mate looks weird. If you read the Kama Sutra, you’ll see it’s kinda like that.
During head-to-head mating, a male cuddles a female and then sprays sperm into her mouth with a modified arm. Once the sperm has been deposited, the female stores it in a container beneath her beak or around the lining of her mouth. This does not, however, mean that the female will always use the sperm of the male with whom she has recently mated. She can store many sperm packets and then choose one to fertilize.
A female cuttlefish prefer to have more than one option to fertilize to creature’s next generation with good genes. During mating season, she will accept many sperm packets and keep them until she is ready to lay eggs.
However, diamond cut diamond. The males have created a counter-tactic: they start mating by spraying a jet stream of water into the female’s mouth to wipe out the previous males’ sperm packets. After that, they will send their own sperm packets, which the female will either take and keep or reject and discard it.
After finishing the mating thing, the female will lay eggs in a place sheltered from currents by coral or rocks. She’ll reach into the cavity and grab the sperm packets, choose the favorite one and fertilize them.
9. They have a short lifespan
After selecting the best sperm packet to fertilize and lay eggs, the female sticks them to objects, such as seaweed or rocks, on the seabed. Then she emits ink on them to make them resemble grapes. Until those eggs hatch, the mom will stay with them.
Cuttles reach sexual maturity between the ages of 14 and 18 months. They spend their short lives (one to two years) in the tropical oceans of Asia, Australia, Africa, and Europe.
10. Cuttlefish can kill you
Cuttlefish is a member of Mollusca phylum, they are classified into about 120 different species. The species comes in different sizes: from the tiny one (3 inches or 8 centimeters) to the giant one (20 inches or 52 centimeters).
Among them, Pfeffer’s Flamboyant Cuttlefish or Metasepia pfefferi is the most venomous. This cuttlefish has a charming and colorful appearance and they are extremely poisonous, its muscles carrying a highly toxic chemical. Metasepia pfefferi is the only species of cuttles that is toxic enough to kill humans
Although cuttles seldom come into contact with humans, their poison is regarded exceedingly dangerous and can be as deadly as blue-ringed octopus poison. They keep their venom in a razor-sharp beak buried beneath the tentacles.
The other different types of cuttlefish include:
– The common cuttle or European common cuttlefish (Sepia officinalis) is one of the most populous and well-known cuttlefish species.
– The Australian giant cuttlefish (Sepia Apama) is endangered, mostly because of overfishing. This largest cuttlefish can be found throughout the coast of Whyalla, South Australia. The Australian giant cuttles only have a two-year lifespan, reproduce once in life, and die after mating.
– Broadclub cuttlefish (Sepia latimanus)
– Reaper cuttlefish or red cuttlefish (Sepia mestus)
11. They walk along the seafloor with arms
For smaller cuttlefish species that can’t swim long distances, walking is a better solution. They can move without getting too far away from the sand cover.
Cuttles swim by flapping their skirt-like fins and regulating their buoyancy with cuttlebone. When they need to move faster, cuttles take water in via their gills and shoot the water out of their siphon which is underneath the tentacles to move by rocket power.
12. Cuttlefish use decoys to defend
Like most cephalopods, cuttles will use ink to protect themselves from enemies when threatened. It creates a smokescreen and discharges a cloud of ink to hide and escape from the predator. But if this is not enough, they will use a decoy cuttlefish.
This decoy is made of ink and mucus. It is smaller, thicker, and has the same shape and size as the cuttlefish. This pseudomorph is used to deceive and mislead the predator while the cuttlefish flees away at the speed of 40km/h. Because making ink consumes a lot of energy, cuttles do not overdo this protective mechanism. Camouflage is still their strongest defense.
The ink from cuttles is used for writing and drawing by the ancient Romans and Greeks. This sepia ink which has a rich dark brown is still used by some artists today.
13. They’re very lazy
Cuttles’ 95% of the time is for resting. This makes them look lazy, but it is actually a wise move. Cuttles only survive a few years, but they grow quickly (10.5 kilograms). So if they do too much activity, they will not be able to reach their full potential.
As a result, they spend most of their time resting, foraging for small prey, and attempting to avoid being eaten by larger predators. Smaller species spend their whole lives on the seabed, looking for food and partners in a small area. Whereas, larger species will sometime swim out into open water to find better territory.
14. Cuttlefish hypnosis the prey
Cuttles eat small mollusks, worms, crabs, fish, shrimp, and other cuttles. Dolphins, seagulls, sharks, seals, fish, and other cuttles are among their hunters.
Even though cuttles usually change their color to camouflage to avoid predators, they also use this ability to hunt prey. When hunting, they transform their bodies into pulsing light and color displays to hypnotize potential prey.
Cuttlefish, like the octopus, hunt with their arms. Two additional tentacles suddenly appear and quickly capture the target! The species have two additional tentacles with suctions on the tips used to catch prey.
You can see how cuttles hypnotize and hunt prey in the video below!
A razor-sharp beak, similar to that of a parrot, lurks behind the cuttlefish’s numerous tentacles. Cuttles use this tool to eat crabs, mollusks, and other hard-shelled creatures. The hidden weapon is especially effective since it contains a toxin that, when bitten, causes prey to freeze in place.
15. Cuttlefish vs squid
Cuttlefish and squid are cousins with 10 arms and they look similar. So how can we distinguish them?
Let’s start with the similarities!
– Squid and cuttlefish are both members of the mollusk class Cephalopoda, which also contains octopus and nautilus. Most cephalopods, unlike other mollusks such as clams and snails, lost their hard outer shells.
– Squid and cuttles are both described as ten-armed cephalopods due to their 8 short arms and 2 long tentacles. Octopuses only have 8 arms.
How about the difference?
– Cuttlefish belong to the order Sepiida, whereas squids are members of the order Teuthida
– Cuttles and squid both have vestiges of their ancient exterior shells, yet these structures are very different. Cuttles have a larger internal shell called the cuttlebone, while squids have a flexible, feather-like structure called the pen within their bodies.
– Squids are fast while cuttles are slower.
– Cuttles have W-shaped pupils whereas squid pupils are circular.
– Squid have streamlined, torpedo-shaped bodies, as opposed to the cuttlefish’s large, thick body.