Animals utilizing external fertilization are typically animals utilizing external fertilization are typically insects aquatic animals land animals animals that reproduce asexually mammals.

 aquatic animals

External fertilization is the kind of fertilization that happens outside the female body. The female will put the unfertilized egg outside and the male will eject the sperm later. 
This will cause the sperm have to mobilize further to the egg than internal fertilization. That makes this method only viable in water or highly moist area.