With amigurumi, you often crochet all body parts separately and then sew all the pieces together at the end. You can use a regular sewing needle, but I think that a yarn needle, which is also sometimes called a tapestry needle is an essential part of your basic crochet materials. It looks like a sewing needle only the eye of a yarn needle is quite large, so it can accommodate even the heaviest yarn. Also unlike a regular sewing needle, the tip of a yarn needle is blunt. This is because a sharp tip would end up splitting or fraying the yarn. Many yarn needles have tips that are curved, but a straight tip also does the job.