When you have upped the size of feeders..

[sunshinegeckos]

Do you leos eat less and sometimes skip a day? I upped my mealworms from small to medium and my pheonix worms from medium to large. They ate less mealworms then they have been and they skipped a day (I feed every day) This is normal right? Its ok you can tell me im a worrier haha

 

[fl_orchidslave]

The larger the prey, the less quantity they will require to satisfy their appetite.

 

[sunshinegeckos]

ok thanks. Thats what I figured

 

[M_surinamensis]

I love prey size discussions, because they involve really easy math that people still find interesting and I have an excuse to use MSPaint.

Reptile digestion! A couple key points:

●Many predatory reptiles don't chew that well. The exact amount of chewing can change from species to species, but with a few exceptions, the shape and arrangement of their teeth, the shape of the jaw are things that have evolved for prey collection, rather than chewing or grinding food. Snakes are the most extreme examples, swallowing their food whole as they do, but a species like a leopard gecko usually gives a prey item a couple chomps to grab, usually kill and line up the prey item, then they swallow it mostly intact.

●Many reptiles have pretty minimal peristalsis, the waves of muscle contractions and relaxation that moves food along the digestive tract; in humans it's partially responsible for more grinding and physical breakdown of food. Our stomachs churn away like anything, rumbling along like a cement mixer in a way that can break food up into smaller parts and that mixes it around so that it is exposed to more digestive juices. Most reptiles, including leopard geckos... it's fairly weak, just enough to move items along through the digestive organs.

●Most predatory reptiles have fairly weak stomach acids (again, some exceptions). Digestion occurs primarily as a result of enzyme action,* with prey items being slowly broken down from the out-side-in in layers, rather than being quickly reduced to a thick paste (as happens when there's a strong stomach acid).



What that all adds up to mean is that size, shape (surface area) and composition of prey items can create pretty dramatically different rates of digestion. The prey goes in, gets chomped a couple times and is swallowed. It then mostly digests from the outside, passing through organ systems as it is broken down.

I have drawn, in paint, an absurd picture of a rectangle, that I'm going to ask you to pretend looks like a mealworm. He is smiling, because mealworms are very stupid and it doesn't know it's going to be eaten. Also, because it's much much harder to draw insect mouth parts than smiley-faces. They also have ridiculous dimensions, just roll with it.

Attachment one- If the mealworms you usually fed were one inch long and one eighth of an inch around, and you moved up to two inch mealworms, you did not double the size of the worm. Twice as long with the same shape and proportions also means twice as tall and twice as thick; 2 x 2 x 2 = 8. When you increase the size of prey items, which will have roughly the same shape when they are little as they do when they are bigger, you increase all three dimensions. Twice as long is about eight times as massive. Obviously the new insects won't always fit into such easy to double up amounts, they may only be one and a half times as long... but it still increases all three spatial dimensions at the same time, so keep the mass in mind.

Attachment two- One of the other things to consider is surface area. Because the items are not that well chewed, the rate of digestion will always be affected (especially initially) by the surface area of the prey items. The greater the surface area, the more of it will be in contact with digestive secretions and the more rapidly it will be digested. Going back to my poorly drawn easymath mealworms, you can see how the smaller mealworms have double the total surface area of the one big one. Which would mean twice the space for enzymes to coat and break down the food.

Attachment three- Finally what should be considered is the relative digestibility and nutritional value of each layer of the prey item. This is a factor which does not necessarily just multiply up as a prey item gets bigger. The exo-skeleton of a small mealworm is often about the same thickness and density/hardness of a larger one. Different prey species can have different rates at which they are digested, in addition to having different nutritional contents. Prey Item A might have a thick, heavy chitinous shell that is more difficult to digest. Prey Item B may have a softer body that's more easily dissolved. Prey Item C might have the thickest shell, but twice the nutrients underneath it. Just as a couple examples, in these diagrams, consider the red areas to be difficult to digest (like an exoskeleton), the green to represent highly nutritional tissue and the grey to be filler or junk tissue with a low nutrient value. These are all just examples, for the purposes of illustrating a concept, they are not accurate representations of nutritional content. The top rectangle-worm has a medium exo-skeleton and average nutritional value. The second one has a heavy exo-sksleton and about the same nutritional content, so it would not be digested as well and the gecko would get fewer nutrients even though the prey item is the same size. The third rectangle worm has the same exo-skeleton as the second, but a higher nutritional content; it is not digested as fast, but once that shell is worked through it's very valuable nutritionally. The fourth has almost no exoskeleton, like a soft bodied rectangle-grub of some kind, easily digested but in this case has a very poor nutritional content, a lot of its mass is junk or filler, it would take two of them to have the same nutritional value as the others.

These factors; size, shape, digestibility and nutritional value are some of the puzzle pieces you can put together in order to identify and construct an ideal diet for your animal's specific needs. They should be considered against such additional elements as the general health and well being of the animal being fed, an underweight animal may need more protein and lipids in its diet, if you have an egg-laying female then choosing prey items for their calcium or vitamin content can be useful, an animal that has been fasting often has a digestive system that has slowed enzyme production and they should be fed smaller prey items with greater surface area and better digestibility accordingly... and so on. And of course, the digestive health of the gecko will be altered by environmental factors, a higher temperature means an increased metabolic rate and should subtly change the ideal diet, the availability of that often touted belly heat can change how efficiently the animal's digestive system is functioning. Add it all up, consider the prey as another variable within your control, pick what's best.


*some of those enzymes are amazing, check out gila monster digestion... seriously, it's very cool.

Edit: Probably help if I included the attachments I kept talking about. Hurp-durp!

 

[ReptileWorld]

its ok for them to skip a day of eating especially when you feed daily. for this reason i feed my geckos every other day and this seems to work well for me and they eat every chance they get. :main_thumbsup: