I can help with the Army
Gino,
I can't help you much with the Marine Corps, but I've got friends who were Marines and after a break in service, joined the Army.
I've been enlisted in the Army for almost 11 years now and currently work for the US Army Recruiting Command (USAREC) 1st Bde, which covers the North East. I have been keeping leopard and fattail geckos for the past 5 years.
First off, the Army has changed quite a lot in the past years, so while good meaning, the info provided by Sybella and Mike is a bit dated.
If you qualify for service (test scores and physical), you've got so many options. First would be whether to join as an enlisted soldier (Private through Command Sergeant Major of the Army; E-1 through E-9 pay grades), or as an officer (2nd Lieutenant through General; O-1 through O-10). Check out the
Pay Charts.
There's benefits to both routes. Obviously after checking out the pay charts, pay is better as an officer, but still not too bad enlisted either. With your schooling, you'll be able to enlist as an E-4, which would still be about $600+ less a month than a 2nd Lieutenant would make. While that's a great amount of cash, you have to figure in other payments, such as housing allowance, Basic Allowance for Subsistence(BAS), clothing allowance (not given to officers), any special proficiency pays, etc. As an E-6, my monthly basic pay is only $2477, but my most recent statement of military compensation has my actual income up around $53k, factoring in all the other benefits above. Obviously the officer pay rates are higher.
As an enlisted soldier, you'll have better choice of your job, over 200 different ones right now. What are you interested in doing; chances are there's something the Army needs. One of the things the Recruiters I work with always say is a benefit to the Army over other services is the amount of jobs we offer as well as the guarantee that we can give over others as far as which job you'll do. You'll truly become a professional in that field specializing in and receiving future training in whatever it is you choose. Your next promotion as an Enlisted soldier will most likely be to SGT/E-5 and would be a Non-Commissioned Officer and you'll likely be in charge of some soldiers and would be the first link in thier chain of command.
As an officer, most often times unless you already have a skill, such as Chaplain, Doctor, Dentist, you won't get a choice of what you do. You could end up as an Infantry, Transportation, Aviation, etc officer after your training. Officers are not really specialists in thier fields at least until they reach a certain level of rank and get branch qualified and only in certain fields. They are general managers and often spend thier time bouncing back and forth between 'Commands' and Staff time from 6 months to 2 years. I'm not an officer and don't profess to know all there is about it, but there are some political aspects to it that you don't usually have with Enlisted positions. However, if you can manage to get guaranteed to work in a field that interests you and like the idea of being a generalist manager, go for it.
As for your herps. I don't know what you keep, but if you don't have good access to a reliable herp sitter that you totally trust, you may consider selling them. Your first 9+ weeks will be in Basic Training, where you won't have many of your personal items, let alone any pets. Then you'll spend the next few weeks to months in Advanced Individual Training where you'll still be living in barracks that don't typically allow any pets or (remote) possibly a fish, depending on the length and location of training. Most barracks will at best allow a fishtank. Depending on your job and location of first duty station, you'll either live in barracks or be allowed to get your own place off post. There's really no way to be sure until you get there. As an NCO, many places are allowing soldiers to live off post, but again, it all depends on how much barracks space there is. That goes for CONUS (Continental US) and OCONUS (Outside CONUS). For officers, they have BOQ or Bachelor Officers Quarters, where they may fall under the same rules; I'm not sure. Post Housing usually allows small harmless animals and dogs/cats. So, if you're into large boids, you may run into trouble in Post housing(It seems to me that each Housing office writes thier own rules, so I can't say it's that way everywhere); but that's if anyone pays attention to what you have in the first place.
One of the biggest obstacles you'll have to keeping your present herps is if you get assigned overseas. Here's a scenario I've just gone through. I received orders for Japan in 99, which is a 3 year tour for married or career soldiers. I was unable to find info on exporting/importing my leopard geckos, so I left them with family and then a friend after family couldn't take care of them anymore. The 21 I left turned out to be about 39 when I returned. I was paying for thier food and care while I was gone, but couldn't enjoy them myself, sell and upgrade stock, etc. So I'm left with many normals, a couple dwarfs, and a couple with what appears to be incubation or calcium deficiency problems. I was able to get some AFTs and Leopard geckos in Japan, for about 3x the price they are in the States, but again, couldn't afford the $500+ to import the few I had back into the States.
Looking back, I probably should've sold the geckos I had before leaving and started all over upon returning. Other than that, I wouldn't trade anything for what I've gotten to experience over the past 11 years. I've been able to live in 4 countries over 3 continents and visit places most other people in the world don't get to go. I've seen herps in the Middle East, Japan, South AND North Korea, and all over the states.
Okay, I'll quit now before I sound like a Recruiter. I've probably gotten off track from your initial question anyhow. If you'd like more info, PM me or email and I'll let you know all I can.