Marine Iguana Care Sheet

Marine Iguana

Scientific Facts

Common Name:Marine Iguana
Scientific Name:Amblyrhynchus cristatus
Life Span:60 years
Size:12-56 cm (4.7-22 in) snout to vent length17-84 cm (6.7-331 in) tail length
Habitat:Steep rocky cliffs, low rock ledges, and intertidal flats
Country of Origin:Galapagos Islands

Physical Description

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The Marine Iguanas have varying physical appearances, and this will depend on the island that they were located. They grow between 50 and 100 cms (20-39 inches) in length, and their weight can reach up to 10 kgs (22lbs). Smaller versions of the Marine Iguanas are often found in Genovesa Island while the largest ones are found in Fernandina and Isabela.

In normal times, they cloaked in black color, but if they are in their breeding season, the adult males will have red and green coloration. The juveniles will have dorsal stripes with light colors. Their scales will be triangular-shaped, and they are known for using their tail as a propelling device when swimming. In the wild, they can be seen with a white substance that has been excreted from the nasal glands, these are just excess salt, and it normally occurs for Marine Iguanas who live in seaside islands.


Several subspecies of Marine Iguanas have been found living all throughout the Galapagos Islands. There are not a lot of studies conducted on them as they can be seen hiding away or gets stressed easily from any indicator of human interaction. Perhaps, the most reliable information that we have is the exact location of these species have been found, as a piece of general knowledge, their sizes, and color differ on where they were found.

A. c. albemarlensis – Found in Isabela Island

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A. c. cristatusFound in Fernandina Island

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A. c. hassiFound in Santa Cruz Island

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A. c. mertensiFound in San Cristobal and Santiago Islands

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A. c. nanusFound in Genovesa Island

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A. c. venustissimuFound in Espanola Island and adjacent tiny Gardener Island

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Eating Habits

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The Marine Iguanas are known to be herbivores, and they have been seen feeding on marine algae that are located along rocky shores and underwater. They also find it easy to find food in shallow, marine waters. Also, they can only eat certain types; they have practiced feeding on various land plants.

The Galapagos Islands is a haven for different algae types like Grateloupia, Gelidium, Hypnea, and Polysiphonia. The male and female Marine Iguanas have varying feeding habits, and this will normally depend on their age. The males will always opt to dive and forage for red algae even risking himself during high tide while the females find food intertidally.

The temperature and the season will always have a great impact on how they hunt for food. Since they only feed once in a day, most of them have become more efficient in looking for food on sunny days even when temperatures are at its highest.

It’s not always a happy day when a Marine Iguana looks for food, as they will usually exert a lot of effort doing so. Not being able to regulate their internal temperatures, after they have hunted for food, they will have to stay in a stationary position to raise their body’s temperature.

While feeding, they will also take in a large amount of salt their bodies will have to take out the salt from their blood and excrete it through their glands.

Sleeping Habits


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Marine Iguanas can be seen sleeping in clumps as a way for them to conserve warmth, and this also serves as their protection against the cold. 

Development and Reproduction


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By age 3-5 years old, the female ones will reach their sexual maturity, and the males’ sexual maturity will begin by age 6-8 years old. A good indicator of sexual maturity will be to notice that their bones are growing big and thick. They can live up to 60 years, but most of them can only live up to 12 years.

Their Breeding season will begin from December to March and the nesting period is from January to April. Their breeding period greatly varies on their location, including the algae-growth. The usual reproduction scene is for them to breed every other year; however if they are presented with a lot of food, females have the capacity to breed every year.

Fighting over other males is also a common behavior during the mating season, large males can be seen defending their territories to prevent smaller males from entering and breeding with the females. The large ones will threaten other males by revealing their reddish interior inside their mouth, walking on stiff legs, and raising their spiny crest.

Most males will back down from a fight, but once in a while, you will find two males willing to fight it out just to have a chance of mating with the female. Biting is not the fighting method for these reptiles; they will push each other away by thrusting their heads.

Their fights can last for a few hours, and they will even have the time to take periodic breaks. After establishing a winner through headbutting, the losing team will accept defeat by doing a submissive position and eventually retreat.

Female Marine Iguanas will always have a preference for mating with big males and their main basis for choosing one will be the body size. Males with large bodies are presumed to have better reproductive performance and will often result in having high survival of large hatchlings.

The females are given the freedom to hop from one territory to another; however, if they are inside one, they are often protected by the male; thus, she will receive less harassment from other non-territorial males.

The courtship period will begin by the male nodding at the female. If she accepts this nod, she will then be mounted while he holds her neck. Their mating will not go beyond 20 minutes, and the usual duration for this is just 3-4 minutes. 

There will be sneaky non-territorial males who will try to squeeze in quick sex with females, and this needs to be rapid. As soon as the large males, find out that there are non-territorial males lurking around his habitat, he will chase them out ferociously.

The males can be happy-go-lucky by breeding with a lot of females while the female will remain loyal by mating only once. A month after successful copulation, females will lay 1-6 eggs while some can only lay 2-3 eggs. They can have their nest sites within a 2km radius inland, but they would normally prefer to have it near the coast. The female prepares the nesting site by digging sand or volcanic ash and is 30-80cm deep.

The eggs will start hatching after 3-4 months, and the size of the hatchling’s ranges from 9.5-13 cm (3.7-5.1 in) and they weigh around 40-70g (1.4-2.5oz). After coming out from the nesting site, they will look for an environment that promotes optimum conditions for feeding, shelter, regulation, and temperature. Some of them can travel as far as 3 km in just 2 days.

How to Breed


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During the breeding season, iguanas are known to be very aggressive to other iguanas and even to their owners. This is just their normal behavior, and breeders should keep in mind that it’s needed to practice minimal handling during their breeding stage. Successful breeding will entail you making an alteration in their environment and diet.

It’s crucial to give your female Marine Iguana an adequate amount of calcium and D3 supplements for egg-laying benefits. The females will normally avoid eating at least 2-5 weeks prior to laying eggs, so you need to ensure that you have fed them well before initiating breeding.

Give them more light exposure and increase humidity and temperature to get their bodies in slowly adjusting to breeding. You should introduce the female iguana or iguanas to the male before you start the actual breeding. Successful breeding will mean that the female becomes pregnant with a visibly a large round belly, this will soon be empty after laying her eggs.

The entire process will take around 65-85 days and after laying all her eggs, bring the female iguana to the veterinarian as it needs to be examined if she laid all her eggs. There will be cases that the eggs get stuck in their oviducts, and these iguanas need to undergo an operation.

The eggs should be placed in an incubator with a set temperature. Once the baby iguanas start hatching, give them a day or tow to successfully hatch from their eggs. Tend to the female iguana as she may feel very thirsty with all that she has undergone and the hatchlings should be transferred to their new enclosures. 

Common Health Problems and Treatment


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Metabolic Bone Disease (MBD)

Metabolic Bone Disease is a complicated one, yet the most common disease associated with Marine Iguanas. The main cause of this is easting food that has a high level of phosphorous yet low in calcium and vitamin D3. Common indicators of this will be swelling of the lower jaw, the jaw and facial bones feel soft, and the hind limbs are also swollen. 

If they undergo X-ray, the findings will expose thin bone tissues, possible fractures that may have happened even with minimal force. While the blood tests will only show a low calcium level with alarming calcium to phosphorous ratio. 

If this disease progresses, the Marine Iguana can be seen twitching its muscles, having seizures, decreased appetite, and lethargy. The juvenile is the one who is inflicted with this disease. Injecting or oral calcium intake may be the only treatment for this disease.

Infectious Stomatitis (Mouth Rot)

A bacterial infection that occurs on the gums and having swollen gums can easily pinpoint to this illness. A Marine Iguana with Mouth Rot will look like they have cottage cheese stuck in their mouths. Although this may not be as severe as the other diseases, getting this treated immediately is essential for the iguana to feel better. A veterinarian might prescribe deworming medicines that can be administered orally or as an injectable.


Having parasites on your pet iguana is probably the most difficult to spot disease as they will not show any clinical sign, and they can only be detected via fecal examination. Parasites can cause diarrhea or weight loss. You may use a magnifying lens as the mites and ticks can be seen moving around the Marine Iguanas skin, and they are found hiding in the head or skin folds.

These can be treated via topical, oral, and injectable medication that should have been prescribed by the veterinarian. You should also clean and disinfect their enclosure all the time.

Respiratory Infections

A Marine Iguana that is constantly stressed by being improperly fed, kept in an unclean tank or has been improperly fed is always at risk of acquiring respiratory infections. You might see your pet iguana sneezing, nasal or ocular discharge, having bubbles in their mouth, unusual breathing, or even gasping for breath and the generic lethargic feeling.

These can be easily discovered by undergoing X-rays, blood, and culture tests. Respiratory infections are treated with oral or injectable antibiotics from the vet.

Hypervitaminosis D

Giving your pet iguana too many vitamins can also pose a great risk. Pet iguanas that have been fed with dog and cat food have been found to have Hypervitaminosis D. Symptoms of this is often vague but will include lack of appetite and feeling lethargic.

As simple as this disease sounds, the treatment is usually serious and will require the iguana to be confined in a hospital with intensive therapy with fluids; one may also force-feed and drugs, this should help the iguana lower down their calcium level.

Unique Diseases found in Iguanas

Cystic Calculi

Normally called the bladder stones, and this is usually a result of excessive dietary minerals that form crystals in the bladders, thus leading to bladder stones. These are composed of uric acid and may be caused by a diet that has too much protein content.

Symptoms of having this disease will include seeing blood in their droppings. A thorough examination that includes X-rays will assist the veterinarian in giving a proper diagnosis. Surgery may be needed, and diet restrictions may be needed to prevent these stones in the future.


The Salmonella infection can be transferred from animals to humans, and the common symptoms include severe gastrointestinal disease, vomiting, abdominal pain, cramps, fever, and even blood poisoning. Those who have compromised immune systems like the children and older people are at higher risk of salmonella infection.

The best way to avoid getting salmonella infection is sanitation. The iguana’s tank should be thoroughly cleaned and disinfected at all times, especially if their substrates have been soiled. Breeders should wash their hands with an effective disinfectant soap every time they handle iguanas.

Avascular Necrosis

Juvenile iguanas usually experience this disease as they are kept in a tank with low humidity. The blood vessels that supply a specific area on the body will get clogged up, thus leading to the death of a specific tissue. Low humidity levels can also result in abnormal shedding of their skin.

Accumulated layers of unshed skin will form around the toes and the tail and will eventually result in restricting blood supply, thus having avascular necrosis. You might notice that their toes become discolored and become infected; it this is left without treatment; it will definitely lead to the iguana’s death. 

The treatment for this is removing the dead, unshed skin, but for severe cases, amputating the affected body part is needed in order to stop the necrosis from spreading.


A common disease on the iguanas, the abscesses happens when bacteria or fungi have been introduced into a bite wound. The sings of this disease will include infected swelling paired with thick pus. Surgically removing or flushing the abscesses are the usual treatments. These are then examined to discover what type of organism caused the infection so that proper antibiotics are used.


This occurs if the iguana has failed to lay all her eggs. Although it has become common in reptiles, this disease can be very serious as this might cost the life of the female iguana. This is normally brought about by improper lighting, temperature, poor diet, dehydration, and a nest site that does not provide all the female’s needs.

You may also need to check if your female iguana has physical abnormalities that may prevent them from properly laying all the eggs. The eggs may also be deformed or oversized and will only end up getting stuck in the reproductive tract.

As a breeder, you need to find a veterinarian that is very well-known in handling cases like this. Surgical procedures may be done to help the female iguana release all her eggs. Having a reliable vet nearby will also be greatly beneficial to your female iguana who is experiencing dystocia.

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Signs of a Healthy Marine Iguana

Clear Eyes

It should be part of your daily routine to observe your pet iguana; the eyes should be crystal clear, free of tears or any discharge. Make sure that it’s also not dry or have crusty debris. Iguanas are naturally observant and will often notice everything in their environment. Surprising as it may seem, but iguanas have a third eye located at the top of their heads. This is called the parietal eye shaped like an oval with an opaque cover. Iguanas use this to detect the predators above them.

Healthy Nose

Iguanas in the wild are often seen sneezing as this is their body’s natural way to remove the extra salt. Small amounts of salt after the sneeze can be observed on their nose. However, if your pet iguana has been sneezing a lot and is paired with excessive nose discharge, this can be an illness symptom thus needs to be checked.

Healthy Skin

Daily monitoring of your pet iguana should assure you that they are free of any parasites, lesions, abrasions, and sore spots. A good indicator that your iguana is perfectly healthy is that it will shed a couple of times in a year depending on his age and size. 

Strong Bones

As mentioned above, iguanas are prone to Metabolic Bone Disease that is usually caused by inadequate calcium, inappropriate enclosure temperatures, and no to little UVB lighting. Provide your Marine Iguana with proper food that contains a healthy amount of calcium.

Pink Mouth

A healthy pink color free on any discharge or infection should be the state inside their mouths. You can do routine check-ups on their mouth to ensure a healthy iguana mouth.

Good Appetite

Healthy iguanas will always be enthusiastic when it comes to feeding, so when you notice a sudden change in their feeding behavior, inspect probable causes like the temperature inside the tank. You may also need to monitor the quality of their droppings as changes in their feces can also mean they are not feeling right.

A happy pet in general

Iguanas are known to be very active and playful. They are usually alert and always observing their environment. They also have a steady phase when walking and capable of moving his arms and legs easily.



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Marine Iguanas are known to be mutualistic and friendly in the sense that they live close together in the wild. They also have no issues with other animals and spend most of the day sunbathing or looking for food.

In the Galapagos Islands, both the Marine Iguana and sea lions have lived peacefully. Some of them will even crawl over sea lions, and it wouldn’t cause any problems. A way of conserving their heat when night falls, they are seen sleeping closely together in groups. Some may even reach 50 Marine Iguanas sleeping cozy together.

If the weather becomes too hot, they will adopt a survival posture. They will face the sun and raise their body. This exposes as little as possible body part, and cool air passes underneath them.


Although a Marine Iguana loves getting exposed to sunlight, they are also well-adept in foraging in cold water while in the Galapagos Islands. They can stay in 11-23 degrees Celsius (52-73 degrees Fahrenheit) at the sea surface. 

Their muscles become less efficient as the temperature drops. And they have been found to have optimal temperature in their bodies for digesting algal food in their gut.

Brumation Cycle

As tropical animals, the Marine Iguanas will generally not hibernate. However, if you notice that they are acting like they want to hibernate bring them over to the veterinarian as this may be a sign that there is something wrong.



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Adult Marine Iguanas can only shed once per year while a young one can shed its skin every 4-6 weeks. Rapid growth will also mean a frequent shed for them. Spraying the enclosure, gentle soaking, and even a bathing routine all done with warm water can be helpful in their shedding process.

Failed shedding will only result in dried and irritated skin and later in fungus growth. Their spikes are normally the main concerns when it comes to shedding because if the skin on these fails to come off, it may lead to breaking and falling off.



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Being the only known sea-going lizard in the world, the Marine Iguana is naturally found on the rocky shores of the Galapagos Islands. They have adapted well to their environment since they have no mammalian predators present in that island. They dwell live the shallow reef and rocky coastlines. 

Marine Iguana as Pets

As interesting as Marine Iguanas can get, they are not the most friendly to have as pets. They can be very difficult to take care of, and they have a higher risk of dying once they are not taken care of properly. Their unique environmental and dietary needs may be the reason why it’s difficult to care for these animals. Good habitat and appropriate feeding may be added to the extra care of your Marine Iguana.

Create the Appropriate Climate

They love sunlight so when placed in a tank, give them enough light exposure. They may need different types of light to ensure survival, one of which is the UVB spectrum. Not having this kind of light may make them suffer from vitamin D deficiency thus being unable to absorb calcium and severe health issues.

You can purchase the UVB lights that have been specifically designed for reptiles, and your Marine Iguana needs to breed naturally with this temperature. The light should be able to reach the whole enclosure. It’s suggested to have this placed at least 12-18 inches (30-46cm) above their basking area.

Having an extra heat source is also beneficial to the wellness of your iguana. The coolest temperature in their enclosure should only reach 75- and 80-degrees Fahrenheit (24-27 degrees Celsius). While their basking area should be 95- and 100-degrees Fahrenheit (35 to 38 degrees Celsius).

Place a thermostat in the middle and on the edge of their tank; this will help you accurately monitor the temperature in different parts of their cage. A cage with a basking spot will help them feel like they are in their natural habitat.

Proper Set-Up

Their tanks should be at least 8 feet by 3 feet by 6 feet (2.4meters by .9 meters by 1.8 meters). The general rule for having them as pets is that their cage should be big. A cage with a small space will only make them sick or depressed since they can’t move around.

Provide their tanks with a carpet that is specifically made for reptile tanks. A cheaper alternative is using newspapers as substrates. Do not use bark, woodchips, treated wood or plastics as your Marine Iguana may mistake this as food and eat them. Large branches and rocks are also good accessories in their enclosures.

Your pet iguana may become heavy so ensure that the branches or structures inside the cage are durable enough for them to climb on. Smooth or flat rocks are recommended as they are comfortable for the iguana to lay on.

A hidden spot is also a great help as there will be times that your iguana feels shy and needs to hide from everyone. Not having this may result in them feeling vulnerable and may not thrive in their environment. A small wooden box is normally enough as a hiding spot.

Putting plants is also a good idea, look for those that will not pose any issues, especially when your iguana eats them. This helps in transforming their habitat into looking like the wild. You have a lot of plant varieties to choose from such as Bamboo, Jade Plant, Dandelion and Aloe.

Feeding your Marine Iguana

Your pet iguanas will eat most vegetables presented to it. You may want to add collards, turnips, mustard, and dandelions in their diet and they will munch on these as healthy treats. They also have a preference for kales and lettuce, broccoli, squash, and green beans. 

Give them vegetables with good nutritional values, normally the colorful varieties of lettuce are a good choice. Fruits will also be a good addition to their diet. Strawberries, blueberries, bananas, apples, and cantaloupes are good varieties.

Dry pellets that have been commercially formulated can also be given to them, and you can mix them in their natural food or have them served separately. The veterinarians will normally suggest that you wet the food first as this will ensure easy consumption for them. 

Store-brought food like the dry pellets should only serve as a food supplement, make an effort to always give your iguana healthy fruits and vegetables. If you notice that your pet iguana is not getting adequate nutrition, you may want to purchase vitamins specifically designed for them. These may be in powder form and can be easily mixed with food.

Keep in mind that giving your iguana too much protein found in their food may give them issues and potentially hurt them in the long run. As herbivores, they don’t really eat meat while in the wild. You need to give them access to lots of clean and fresh water. You can place a large water bowl in their tank since this will also help in increasing the humidity level.

Avoid Problems in their Enclosure

In the wild, the Marine Iguanas can be seen living together. However, once they are in captivity, multiple iguanas should not be housed together as they might fight and injure each other. You can try housing multiple iguanas in the same room, but they still need to be placed in different cages. If it’s really needed for you to place them together in one enclosure, you may want to consult this first with a veterinarian.

Wash the food and water bowls before you replace them with new ones; you can use a light detergent that is not harmful to them. Their cages should be cleaned on a regular basis to ensure their health. Replace their soiled substrate every week and immediately replace broken branches.

Availability – Where to Get One

There are a few pet stores that offer Marine Iguanas, but just like what we have mentioned, these are not really intended to be as pets, so you need to make sure that their tanks are of optimum condition. Mimic their natural environment should you decide to have one as a pet.

Conservation Status

Marie Iguana’s population has always been vulnerable, but the introduction of the Galapagos Marine Reserve in 1998 has somewhat improved. Birds have always been their predators, and this includes hawks, owls and herons. Captive iguanas are in danger because of cats, rats, dogs, and even pigs. 

The Charles Darwin Research Station has conducted studies that will measure the Marine Iguana’s stress levels. Their stress level rises as the El Nino phenomenon is present. Likewise, when there is prominent human activity in their area. As their stress level rises, this also gives more complications with their reproduction such as the eggs not being fully fertilized, or only a few eggs are being laid.

Fun Facts on Marine Iguanas

Marine Iguanas are known to be endemic to the Galapagos Islands, and they have been known to be the only marine lizard species in the whole world.

Diving more than 65 feet (20m) underwater is a piece of cake for them.

Their blunt snouts have helped them with feeding on algae found underwater. While their flattened tails help them in swimming efficiently.

They will only spend a few minutes of underwater eating, but they can be seen spending up to 30 minutes submerged. 

It’s believed that about 4.5 million years ago, they evolved from land iguanas that have been brought in the Galapagos Islands. With this introduction to a body of water, they have learned how to become sea-faring to have a better survival rate in the islands.


Can I place a Marine Iguana and a cat in the same room?

Technically, the answer to this would be no. Your pet cat most likely will bother your Marine Iguana. If your iguana is still young, the cat may be a threat to it while if it’s an adult already, it might be aggressive to your cat. They should be separated at all times.

How can I tell the sex of my pet iguana?

One good way for distinguishing adult males in that they have enlarged femoral pored on the inside of their thighs on their back legs. This looks like a line of warts, and the females will not develop these ones.

Is it okay to clip the Marine Iguana’s claws?

You can do this, but you need to wear protective gloves and goggles as you don’t want claws flying around. These can become very sharp as well, and you might need to have your pet iguana relaxed since one wrong move can easily startle them and may harm you.

Do Marine Iguanas eat bananas?

Yes, they will eat bananas, but you can only give these once a week and give them a lot of varieties of fruits and vegetables of fruits to munch on.

Do Marine Iguanas like to be held?

The direct answer to this is no they don’t like being held, but the good thing is that they might get used to it. It can be a struggle the first few times that you try to handle them but give them enough time to adjust to you and slowly, they will get used to it.

Do Marine Iguanas have to stay under the light all the time?

Their light exposure doesn’t need to be all day. You can play with them outside or be given a bath. If you notice that its stomach feels cold after about 20 minutes of being away from light exposure, that is already an indication that it needs to be back in its habitat. A rule of thumb is that you should never keep it out for more than half an hour.

What if the Marine Iguana gets a mouth rot?

If you’ve noticed that the mouth rot is just in the initial stage, you should swab it with hydrogen peroxide and betadine. Increasing the temperature may also help in their mouth rot.

How can one Marine Iguana be stopped from being scared if the other iguana is not around?

Since Marine Iguanas are friendly creatures with their own kind and depression may arise if their friend iguana leaves. You may want to put a t-shirt in their tanks to imprint it with their scents then put this on the tank with the upset iguana.

Can Marine Iguanas eat small fish?

No, they are herbivores and will only eat fruits, vegetables including leafy greens.

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