I would like to give you some advice based on my many years of experience in the field of education. Ask to meet with your teacher at her convenience about some ideas you have. Make sure to be a good student in class and do what you are asked before the meeting. At the meeting, present your research and offer it to her. Tell her your personal story and your passion for the hobby and your future profession. Ask if you could work with her on setting up a place for the turtle to take up residence. Show her a drawing of the new setup. Offer to start a club in order to get other students interested in her class. I will also offer anY assistance possible with equipment. Letters are fine, but face to face, eye to eye, is the way to handle this situation. If all else fails, ask her if you can adopt the turtle and move it elsewhere, possibly another classroom where you have developed a positive relationship with another teacher, it doesn't have to be a science room.
Your new club could do a fundraiser to purchase new equipment for the turtle and possibly other projects. Don't give up, be positive, and get involved in your school by taking a leadership role. Please keep me posted and let me know if you need any help.
One last thought, I wouldn't go to the principal or school board yet. If she is not responsive, have one of your parents contact her to ask her why she is not "lighting fires" in her classroom, educators should never attempt to turn off students and their passion. If you nurture this student-teacher relationship, you may make a life long friend. By the way, you need to get a teaching certificate after graduation and become the teacher you want right now!
One last comment for now, have you ever seen an unhealthy doctor. The answer is yes, but that doesn't make them a terrible doctor. I'm sure your teacher is extremely knowledgeable in the field of biology. Sometimes even the best teachers miss the mark on teachable moments, especially during the first week of school.
KEEP ME POSTED!