在 types / kinds / sorts of 后面用单数、复数或不可数名词: 

How common are these types of illness OR illnesses? 这些类型的疾病有多常见？

Which types of software will be most suitable? 哪些类型的软件最合适？

——以上摘自《朗文高级英语应试词典》

所以，在Some types of camel have two humps and others have one.这个句子中的 camel用单数或者复数都可以。