Abstract: A modular animal habitat for crawling animals, such as ferrets and lizards. The habitat includes relatively large housings and relatively smaller tubes attachable to the housing. Housings and tubes have flat rear surfaces, and either or both housings and tubes have keyhole slots for accepting common fasteners, so that a modular habitat can be mounted to a vertical surface, such as a building wall. Some tubes have right angles built thereinto, so that the final assembled habitat can span perpendicular walls. The housings are designed so that the tubes are connected to housings at the rear, so that the tubes will be located against the wall. The housings have ventilation holes lined with an absorbent material, such as charcoal impregnated fabric. The housings have food, water, and waste trays which are pulled out therefrom. The housings also have fixed and slidably opening windows for visibility and access. Friction fit connectors are provided to mate and thereby extend plural tubes.