“There are several factors, which may not be immediately obvious to the casual reader, that need to be considered. Firstly, Adam did not have to go out and round up or track any of these animals. Genesis 2:19 clearly states that God brought the animals to Adam. Secondly, although many objectors have claimed that the species Adam had to observe and name would have numbered in the millions, the actual number would almost certainly have been only a small fraction of this.
Note that Scripture explicitly states that Adam named all the ‘livestock’ (Heb. behemah), the ‘birds of the air’ (Heb. oph hassamayim) and all the ‘beasts of the field’ (Heb. chayyah hassadeh). There is no indication that Adam named the fish in the sea, or any other marine organisms, nor any of the insects, beetles or arachnids. In fact, of the two million known species, 98% are invertebrates, which include a variety of animals from sponges, worms and jellyfish, to mollusks and insects. The remaining 2% are vertebrates and number approximately 40,000 species.2 This number is further reduced when the 25,000 marine vertebrates3 and four thousand amphibians4 are discounted, since they clearly do not fit into any of the categories of animals listed in Genesis 2:20.
In addition, assuming that speciation has been an on-going occurrence since Creation, the eleven thousand vertebrate species in question would have most likely descended from a much smaller number of proto-species. Each would be the ancestors of animals in the group that taxonomists call a genus5 (or possibly the higher taxonomic order known as a family6) and what the Genesis account calls a ‘kind’.7 Since many genera contain dozens, even hundreds, of species, it is far more likely that Adam had to name only a couple of thousand of these proto-species—a task which could easily have been achieved in a few hours. (Assuming Adam had to name 2,500 proto-species (genera), and he named a single proto-species every five seconds, it would have taken him approximately three hours and forty-five minutes to complete the task if we include a five-minute break every hour.)”
http://creation.com/how-could-adam-have-named-all-the-animals-in-a-single-day
