Best Substrate for Hermit Crabs – Avoid Deadly Mistakes


Coenobita variabilis

Uploaded to Wikipedia Commons by Vanessa Pike-Russell

I’ve had the good fortune of working with many species of terrestrial Hermit Crabs, including the unbelievably huge Coconut Crab (Birgus latro).  Most are surprisingly long-lived – for example, the species most commonly sold in pet stores (the Caribbean Hermit Crab, Coenobita clypeatus) can survive for 20 or more years if properly cared for!  We’ve learned a great deal about Hermit Crab captive needs over the years, but serious mistakes are still commonly made when it comes to hermit crab substrate choice.  The ability to successfully molt and form a new exoskeleton, and to survive the attacks of cage-mates during this dangerous time, hinges upon the substrate.  Even if all else is perfect, Hermit Crabs will expire long before “their time is due” if they do not have access to appropriate substrates of the correct depth.
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Providing Clean Water to Reptiles and Amphibians – The Nitrogen Cycle


Mexican Axolotl

Uploaded to Wikipedia Commons by ZeWrestler

Successful aquarists know the importance of monitoring the nitrogen cycle, and the lessons I learned while working for fish importers and sellers have served me well when caring for all manner of creatures.  When I began my career in zoos, I was surprised to find that reptile and amphibian keepers, while aware of the necessity for clean water, did not generally pay attention to understanding water chemistry and its effects on animal health.  That situation is much changed today, but professional and private herp keepers can still take some lessons from our aquarist friends. Awhile back, I helped establish an amphibian exhibit at the Maritime Aquarium in Norwalk, Ct.  I was not surprised when the aquarists there, despite lacking prior amphibian experience, excelled at their care and breeding.  Today we’ll look at how the nitrogen cycle functions and review some useful care techniques and products.


How Critical is Reptile and Amphibian Water Quality?

It’s important to understand that most amphibians, especially largely-aquatic species such as African Clawed Frogs and Mexican Axolotls, absorb water and dissolved chemicals over a much greater surface area than do fishes (scale-less fishes, such as eels, loaches and most catfishes, are similar to amphibians in this regard).  In fact, when we administer fish medications to aquatic amphibians, we always begin with a 50% or so dose…the amount recommended for fishes might kill or injure amphibians.


It follows that amphibians are often more sensitive to ammonia and other water-borne toxins than are fishes. My experience bears out the fact that ammonia poisoning is responsible for a great many sudden, unexplained amphibian pet deaths.  Reptiles are less susceptible to water quality problems than are amphibians, but certain species, such Tentacled Snakes and Soft-shelled and Fly River Turtles, seem sensitive to ammonia and pH levels.


Fly River Turtle

Uploadedto Wikipedia Commons by Faendalimas

What is the Nitrogen Cycle?

The nitrogen cycle can be summarized as the process by which nitrogen is converted to other organic compounds that are then utilized by plants and animals as food.  Nitrogen enters the water via dead animals and plants, decaying food, and animal feces and urates.  In herp enclosures, animal wastes are usually the primary sources of nitrogen.


Ammonia, the most toxic of the nitrogen-based compounds, may be ionized or un-ionized; it is most dangerous to aquatic animals in its un-ionized form. More of the water’s total ammonia becomes un-ionized as the temperature and pH increases.

Two types of aerobic (air-breathing) bacteria, which live on gravel, filter pads and other substrates exposed to oxygenated water, control the nitrogen cycle. Collectively, they are termed nitrogenous bacteria.


Nitrosomas bacteria convert ammonia to less-toxic compounds known as nitrites.  Nitrobacter bacteria convert the nitrites to nitrates.  Nitrates, the end product of the nitrogen cycle, are the least toxic of the nitrogenous compounds.


Managing the Nitrogen Cycle in Your Pet’s Home

Aquarists use the term “conditioning period” to describe the time that it takes for healthy populations of both types of nitrogenous bacteria to become established in a new tank.  This period varies in length, but usually falls in the range of 2-6 weeks.


Your aquarium’s conditioning period may be shortened by the addition of commercially-available live aerobic bacteria.  I’ve had good experience with Biozyme Freshwater Bacteria and Nutrafin Cycle.  Micro Lift Bacterial Water Balancer, specifically formulated for turtles, should also be considered.


You can also help the process along by introducing filter material from a well-conditioned tank and, where conditions permit, by using “live rock” and “live sand” (please post below for further info).  The frequent use of water quality test kits is essential. The pH level should be checked often as well, since the water may become acidic during the conditioning period.



Undergravel Filters

Although some of my younger readers will no doubt consider me a dinosaur for saying so, I still use and recommend undergravel filters in many situations.   They are simple to maintain, largely invisible to the eye, and essentially turn the entire substrate into a giant biological filter.  Where useful, power heads can be added to increase water follow though the gravel bed or to create a reverse-flow system (please see the article linked below).


Many public aquariums still maintain huge exhibits with undergravel filters alone.  At various zoos and in my own collection, I have used undergravel filters on large exhibits housing Tentacled Snakes, Northern Water Snakes, adult Snake-Necked Turtles, Largemouth Bass, and other creatures that are very hard on water quality and clarity.


I also favor fluidized bed filters, which are mounted outside the aquarium. They rely upon the same principles as do undergravel filters, and are especially useful where substrate is not used in the enclosure.




Further Reading

Using Undergravel Filters in Reptile and Amphibian Terrariums 


Using Bottled Aerobic Bacteria

Vitamin D3, UVB and Pet Reptiles: Important New Information for Pet Owners

Brown Anole

Uploaded to Wikipedia Commons by Hans Hillewaert

We’ve long known that many reptiles need Ultra Violet B (UVB) light exposure in order to manufacture Vitamin D3. Vitamin D3, which is essential for proper calcium uptake, is also present in many foods, and some reptiles can utilize it in this form.  However, there are some gray areas.  It seems that reptiles long considered incapable of using dietary D3 (and which therefore need UVB light exposure), can sometimes obtain D3 from their diet (please see chameleon and day gecko articles linked below).  Generalizations can be misleading – for example, the study summarized below shows that two anole species sharing the same habitat obtain D3 in very different ways.


Anole Study – Vitamin D3 and Basking Behavior

A study recently published in the Journal of Herpetology [47 (4) 524-29, 2013] examined whether the level of Vitamin D3 in the diet would affect the basking behavior of two anole species.  Earlier research had shown that Panther Chameleons do alter their basking behavior in response to blood levels of Vitamin D3; please see the article linked below for details.


Wild and captive Brown Anoles, Anolis sagrei and Stripefoot Anoles, A. lineatopus, living in Jamaica were used as study subjects.  When the D3 content of the diet was increased, Brown Anoles decreased the amount of time they spent basking in UVB light.  This remained constant over a 6 week period.  This indicated that they were obtaining enough D3 from their diet. When the dietary D3 was decreased, the Brown Anoles increased their exposure to UVB, so as to be able to manufacture D3 in the skin.


Stripefoot Anoles, on the other hand, did not decrease their basking time when fed high levels on D3, and they did not increase basking behavior when fed diets low in D3.


The researchers therefore concluded that Brown Anoles are able to use dietary D3, while Stripefoot Anoles cannot.  Stripefoot Anoles seem to rely upon the Vitamin D3 that is produced in their skin when it is exposed to UVB light.


Studies such as this show us that we must carefully research the needs of each species under our care.  Even if they are closely related, and share similar habitats, diets, and lifestyles, captive conditions that work for one could spell doom for another.


Madagascar day Gecko

Uploaded to Wikipedia Commons by Manuel Werner, Nürtingen, Germany

My Experience: Day Geckos Without UVB Did Well

I’ve made some related observations on Madagascar and Standing’s Day Geckos.  UVB exposure has generally been considered critical to their welfare in captivity.  Yet a colony of both, living at semi-liberty in a large zoo aviary, seems to be doing very well without access to UVB light.  Please see the article linked below for further details.


Providing UVB to Lizards and other Reptiles

Natural sunlight is the best source of UVB, but it is important to bear in mind that overheating can occur quickly, and that UVB does not penetrate glass or plastic.  Reptiles housed or placed outdoors must also be protected from rats, raccoons, dogs, cats, crows and other predators.  Where conditions permit, screen cages offer a great means of providing natural UVB to your pets.


t255908UVB Bulbs

In recent tests, the Zoo Med 5.0 and 10.0 Bulbs were found superior to several other models.  Mercury vapor and compact florescent bulbs generally emit higher levels of UVB than traditional florescent bulbs, and they broadcast it over greater distances.  Mercury vapor bulbs also produce heat, and so may eliminate the need for an additional heat source.




Further Reading

Chameleon Basking Behavior Influenced by UVB Needs

My Notes: Day Geckos Thrive Without a UVB Source

Using Compact UVB Bulbs

 Using Screen Cages


Keeping the USA’s Longest Snake: Eastern Indigo Snakes as Pets

Eastern Indigo Snake

Uploaded to Wikipedia Commons by Arjuno3

Hi, Frank Indiviglio here.  I’m a herpetologist, zoologist, and book author, recently retired from a career of over 20 years with the Bronx Zoo.  The magnificent Eastern Indigo Snake, Drymarchon couperi, is the longest of all snakes native to the USA, but occupies one of the smallest ranges.  These facts, along with stunning coloration and its reputation as a responsive pet, place the Indigo on the wish lists of serious snake keepers and zoos worldwide.  I had the good fortune to assist with an Eastern Indigo breeding/release program headquartered at the Bronx Zoo, which was both fascinating and frustrating.  Today I would like to pass along some thoughts on its natural history and captive care.


The Eastern Indigo Snake is among the longest of all North American snakes; in the USA, only the Bullsnake, Pituophis catenifer sayi, regularly rivals it in size.  Robust and alert, the Eastern Indigo Snake averages 5-6 feet in length, with a record of 8 feet, 5 inches.  The glossy, blue-black coloration is unique to this species.  Some individuals, greatly favored in the pet trade, sport heads and chins highlighted by a reddish tint.

Natural History

The Eastern Indigo Snake is restricted to southeastern Georgia, southeastern Mississippi, and Florida.  Although coastal dunes, Palmetto scrub, agricultural areas and marsh fringes are colonized, healthy populations seem to require large expanses of longleaf pine forest and similar upland environments.  Human development within prime Indigo habitat has severely threatened this species’ future.  Today, only captive-born individuals may be legally sold, but over-collection was a severe problem in the past.

The Texas Indigo Snake (D. corais erebennus) ranges from southern Texas to central Mexico, while other relatives, known as Cribos, inhabit Central and South America.

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Are Tarantula Bites Dangerous? Sometimes Yes, According to New Study

Are Tarantula Bites Dangerous? Sometimes Yes, According to New Study


P regalis

Uploaded to Wikipedia Commons by Morkelsker

Hi, Frank Indiviglio here.  I’m a herpetologist, zoologist and book author, recently retired  from a career of over 20 years with the Bronx Zoo.  I’ve worked with thousands of tarantulas, in zoos and my own collection, for over 50 years.  In all that time, I’ve never been bitten…mainly because I do not handle them!  Tarantulas certainly adjust to captivity, but they can in no way be “tamed” or “trusted not to bite”…videos and statements to the contrary should be ignored.   Cases involving muscle spasms, chest pain and other severe reactions requiring hospitalizations were reviewed in a recent study – I am aware of similar cases involving colleagues working in the field.  The urticating hairs of New World tarantulas are also a consideration; some years ago, a co-worker of mine required corneal surgery to remove those shed by a Red-Kneed Tarantula.


Indian Ornamental Tarantula Bites

In a recent incident reported in the journal Toxicon (an excellent resource for those interested in venom and venomous creatures), a man in Switzerland was bitten on the finger while feeding his pet Indian Ornamental Tarantula, Poecilotheria regalis.  He felt little pain at the time, but experienced hot flashes 2 hours later.  Within 15 hours, he was hospitalized with muscle spasms and chest pain.  He was treated with muscle relaxers, but muscle cramps continued for an additional 3 weeks.


Researchers at the Swiss Toxicology Information Center became interested in the case and decided to investigate further.  They turned up 18 additional reports of severe reactions to the bite of the Indian Ornamental Tarantula (a/k/a Indian Ornamental Tree Spider) in their organization’s records and reported in medical journals.  Spider care websites contained anecdotal information about 18 other bites from the same species.


Most of the bites were to pet-owners’ hands, but thighs, cheeks and shoulders were also bitten (I imagine this to be the result of foolishly letting spiders wander about the body).  In 58% of the published cases, muscle spasms were suffered by bite victims.  Cramps continued for 1-4 weeks after discharge from the hospital.


Tarantula Venom

When corresponding with tarantula owners or training zookeepers, I always stress the fact that spider venoms are quite complex, and we that know very little about those of even commonly-kept species. Antivenin is, in most cases, not available.


P metallica

Uploaded to Wikipedia Commons by MLursus

Also, spider venom may evolve in response to the reactions of prey species, as has been shown to occur among many venomous snakes.  This may affect how bites should be treated, but specific information is scarce.  Venom composition (and, therefore, the necessary treatment) may vary among different populations of the same species…again as occurs in venomous snakes.  Individual sensitivities to tarantula venom, another unstudied subject, must also be considered.


As numerous species may be sold under the same common name, and exact identification is often difficult, it is critical that you ascertain the Latin names of any tarantula under your care.


Urticating Hairs

North and Latin American tarantulas shed tiny barbed hairs when agitated.  I saw x-ray images of such hairs imbedded in my co-workers eye (please see above).  At the time, I was undergoing a cornea transplant (non-spider related!), and being treated by the same surgeon who had operated on my co-worker.  According to the surgeon, tarantula hairs that work their way into the eye are extremely difficult, and in some cases impossible, to safely remove (in 2009, doctors were unable to remove the hairs of Chilean Rose-haired Tarantula from the eye of a victim in England).


P. subfusca

Uploaded to Wikipedia Commons by mistic

So please…enjoy observing and studying tarantulas, but do not touch them.  Please see the articles linked below for information on how to safely keep and transport these fascinating creatures. 


Snakes: Venomous Bites and Human Predation

Two surprising studies examining venomous snake bites and snake predation on humans:


Venomous Snakes Bite 4.5 Million People Each Year


People as Reticulated Python Prey: Study Documents 150 Attacks, 6 deaths in the Philippines




Further Reading

Tarantula Care: Popular Species

Important Supplies for Tarantula Keepers

Interesting Tarantula Facts

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