Feeding amphibians and Cultures of invertebrates

Materials produced by: Gerardo Garcia, Durrell Background

Amphibian nutritional requirements unknown

Stomach contents best we have in most cases

Few studied throughout the year, life time

Incredible diversity of species Feeding Considerations

• What will they eat?

• Can I supply enough of the food item all year long?

• How is the food going to be offered? Are they eating?

• Hand feeding

• Counting the food in and out

• Presence of feces

• Periodic massings Supply and Demand

• Variety is the spice of life.

• To culture or not to culture How is the food going to be offered?

• Hand feeding

• Broadcast feeding

• Feeders Diet

All adult amphibians are carnivores

Larvae (tadpoles/efts) may be herbivorous, carnivorous, omnivorous or pass through one or more diet preferences throughout development

Dietary items are mostly invertebrates of appropriate size but large species can consume vertebrates including other amphibians, reptiles, birds and small mammals

Amphibians capture their prey with a sticky tongue or directly with their jaws and swallow their prey whole, often alive Food composition

• Water • Protein • Carbohydrates • Fats • Minerals • • Hormones • Toxins • Indigestible – chitin –fiber Water Carbohydrates

• Important Nutrient Provide Energy • Makes food Palatable Digestible Sugars • Facilitates intestinal motility provide energy • Facilitates absorption of vitamins, sugars Indigestible Sugars Cellulose • Important to evaluate nutritional components Important to peristalsis in diet on dry weight basis Largest nutrient by weight and volume Often overlooked as a nutrient Provides no energy (calories) If not present in sufficient quantity: Not palatable Poor intestinal motility Poor absorption and distribution of sugars, B-vitamins and other water-soluble nutrients Must compare food on a dry matter basis to see accurate content of nutrients in food Proteins

Amino Acids Building Blocks Low protein diets Muscle weakness Cardiac arrhythmias Hydrocoelom Poor reproduction Skin lesions (collagen tears) Immunosuppression High protein diets (unbalanced) Gout (excess purines) Excess water demand to flush out nitrogenous wastes (ammonia, urea, uric acid) Fats

Provide most energy per gram Essential for building cell membranes Too much causes corneal lipidosis Minerals

Calcium, , , , , etc Maintain osmotic pressure essential in skeletal formation Acid-base balance Can replace each other in metabolic pathways Calcium Recommendations

• • Fine grade – Pharmaceutical grade only – Powdered form has higher – Certified free of metal clingability contaminants • Probably unnecessary to • supplement with lots of Ca every • feeding – Rotate with low calcium- mix General ‘rules’ of feeding

Present all diet in a whole, natural, state wherever possible

Present invertebrate prey live – chilled and dusted with multi- vit/mineral powder or gut-loaded

Present vertebrate prey dead – thoroughly defrosted and at room temperature

Provide as varied a diet as possible to minimise the risk of deficiencies – supplement commercially produced invertebrates with wild-caught ‘sweepings’ from pesticide free habitats

And don’t forget to feed the invertebrate prey first. Don’t feed them to the amphibians first if weren’t feed correctly/abundantly during the last 48 hours Nutritional Disorders Common

• Metabolic disease (MBD) • Obesity • Immuno-suppression Metabolic Bone Disease

Symptoms bone loss rubbery jaw/ fractures seizures tetany Causes inadequate D3 inadequate UVB other minerals replacing Calcium in metabolic pathway

Preventing MBD Appropriate Calcium to phosphorus ratio 1.5:1.0

Vitamin D3

Some amphibians need UVB Obesity • Very Common • Keepers frequently overestimate amphibians’ metabolic demands • Food to fatty or rich in carbohydrates • Bloating • Fat deposits • Renal gout • Lipid deposits in the eyes • Don’t feed out rodents – common mistake (it is really cool to see a frog eat a mouse) – rodents have extremely high fat content Immunosuppression

Common effect of dietary problems Opportunistic organisms like bacteria or parasites to flourish Result is that the underlying nutritional problem is overlooked in necropsy Important to have good communication with vets, keepers, and pathologists Supplements

Dusting Fine powdered supplement Food bowl can wash off items must be eaten quickly

Gut loading gut loading diet fed to crickets supplement doesn’t wash off less available crickets must be eating for 48 hours before fed out cricket must only be offered gut loading diet extremely high calcium content inappropriate for cricket maintenance diet Storing Supplements

Quality of powdered supplements degrades when exposed to heat, moisture or light.

Do not store vitamins in areas of heat (>80Fº) and moderate to high humidity. Store in cool, dark, dry places

Many vitamins are photosensitive and must be kept in the dark or in brown glass bottles

Least stable vitamins are B1, B9, A, E and K

Consider purchasing smaller amounts Supplements

High calcium supplement with approximately 1.5:1.0 calcium to phosphorus ratio

Lots of commercially available pet products available. Unfortunately many are not effective.

Human supplements are regulated. Unfortunately the products are not formulated for amphibians. Food Sources

• Catching your own • Commercially Produced – greatest variety – least labor intensive – may be closer to wild diet – can be extremely reliable –most fun – expensive – seasonally availability? – availablity? – Pollution • Culturing your own – insect chemical defenses –reliable – more control – more labor intensive Collecting Your Own

Field Sweeping

Light Trap

Tuley Funnel

Infested logs/termite traps Domestic Crickets Acheta domestica • Can be maintained in variety of sizes • Gut loading diets available • Easy to maintain • Palatable • Do not allow excess to remain in cage

Housing Crickets

• Utility tub, wood box, glass aquarium, dresser drawer • Line top with smooth packing tape • Gut-loading diet available • Do not allow uneaten crickets to remain in enclosure Breeding Crickets

• Shallow plastic container (shoebox) • With metal screen cover • Substrate of damp vermiculite, peat moss or potting soil • Place egg laying trays in adult container overnight • Remove and incubate at 30C • 10-12 days later baby crickets

Fruit Flies Drosophila melanogaster or heidii

• Deformed wing or missing wing • commercially available medium • Basic formula: 1part brewer’s yeast to 10 parts potato flakes mix with water 1:1 by volume • Coffee filters for lids • temp 24-25C • May have to protect from ants Springtails, Collembola • Carbon/plaster substrate • plastic boxes with small amount of ventilation(covered) • Broken chunks supply hide spots • Keep damp • Feed brewer’s yeast or fish • Flakes standing water at bottom of cup • spring tails can be poured off into cup Some examples of Drosophila formula (internet)

1 cup banana (about 2 bananas) 1 cup apple sauce 1/8 cup vinegar (or 2 tablespoons or 15 ml) 2 cups oatmeal

Put the banana and apple sauce in blender or bowl and mix until the banana is liquified. Heat in the microwave for approximately 2 min. or until hot enough to kill off any wild fruit fly eggs that were in the bananas, and to reduce mold. Add the vinegar and mix in oatmeal until it becomes firm, but still moist. I then put the mixture into a large freezer bag and keep it in the fridge.

When it's time to make a culture, I scoop what I need and put it in the culture container (usually microwaving it a bit to warm it up). I then mix up a cup of sugar water and throw a few pinches of bakers yeast on top. After a few minutes of letting it 'activate' I scoop some of it off the surface and drip it over the surface of the media. Some examples of Drosophila formula (internet) II

3 bananas 1-2 cups of water 1 cup of oatmeal (Avena sativa) 1 cup of brewers yeast (Saccharomyces cerevisiae) sometimes I mix in: 1 spoon molasses 1 tea-spoon Spirulina 1 tea-spoon milk powder beer (instead of water)

This gives me 6-10 culture bottles. Paper/ excelsior etc for the flies to climb on. Wet kitchen tissue with rubber band as lid 3 minutes in micro. Then into freezer (if I dont need all at once)

Comment: Spirulina changes color from green to yellow when the right temp is reached in the micro oven. Comment 2: Milk powder enhances production, but unfortunately also smell. If you are sensitive to the smell of baby diapers, you should probably not try the milk powder. Some examples of Drosophila formula: The easy…and expensive option

Larval Amphibian Diets

Even more poorly known than adults Tadpoles Detritivorous Herbivorous Carnivorous Cannibalistic morphs Oophagous Etc. Larvae Carnivorous Cannibalistic morphs Laval Caecilians • Very little known about wild diets • Seem to be precocial or mothers’ provide nutritional support • Feed very much like little versions of the adults • Aquatic species can be fed with the same diet for caudata larvae • Sometimes with red meat (e.g. heart beef) Larval salamanders

• Carnivores

• Cannibalistic

• Aquatic larva require small aquatic food – brine shrimp – black worms – white worms – grindal worms – daphnia –microworms Night Crawlers (Lobe Worms) Live Black Worms Live Blood Worms

Live Tubifex Worms Daphnia and Scuds White Worms

Live Grubs Live Wild "Bugs" Live Crickets

www.caudata.org/ Tadpoles

• Greatest variety • Filter feeders • Flake fish foods • Algae powders • Dark leafy greens (avoid spinach, kale and cabbage) • SeraMicron Culturing Brown Algae

Seeding the tank Feeding

PVC Pipe

Tadpole standard diet measure “parts” in weight, not volume

10 parts fish flakes 8 parts trout pellets 8 parts grass pellets 3 parts cuttlefish bone 1-2 parts Tubifex (dependant on availability) 1-2 parts river shrimps (dependant on availability) 2-3 parts Spirulina algae How is the food going to be offered?

Hand feeding can keep close track of food intake labor intensive not always possible Broadcast feeding easiest can be timed to coincide with mist or rain harder to monitor animals’ food intake Feeders can be used to prolong feeding period encourages more natural feed behaviors can be used to condition animals to display better Examples: plastic tube, box + branches, bamboo, plastic balls,… Obligate Carnivores

Must consume animals, not plant material Adapted to diets high in protein and fat and low in carbohydrates Cricket, 65% protein, 14% fat and 9% Acid Detergent Fiber (ADF) Mouse, 57% protein, 40% fat and 3% carbohydrates.

These animals have evolved consuming whole prey rich in protein and very low or devoid of carbohydrates Derive most of their circulating blood glucose from gluconeogenesis Primarily utilizes amino acids as substrate Similar to felids, birds of prey and other obligate carnivores May have unusual essential amino acids E.g., in felids

All adult amphibians are obligate carnivores Although Hyla truncata consumes fruit No data as to capacity to use fruit as energy source Things to Remember

Adult amphibians’ wild diet likely varies by season and by year

In the wild, fasting is common for weeks to years Estivation, hibernation

Wild diets are very different from captive diets Captivity uses limited prey base Captivity makes assumptions about nutritional needs Captivity often results in nutritional diseases unreported from wild: corneal lipidosis, metabolic bone disease, obesity, cachexia, hypovitaminosis Things to Remember

• If it doesn’t look right and taste okay, the amphibian won’t eat it!

• Nutrient consumption is on a rolling average, not an exact daily intake – Balance on a kilocalorie basis

• Corneal lipidosis common due to excess cholesterol intake

• Obesity common due to misunderstanding of metabolic rate of amphibians ‘Tricks of the trade’ for problem feeders

Increasing temperature by a couple of degrees (rarely decreasing)

Increasing humidity and providing ‘rain showers’ – often in conjunction with above

Increasing photoperiod

Decreasing light intensity (rarely increasing)

Alter feeding times – dusk for crepuscular and nocturnal species

Vary the food items offered and presentation