Here is an interesting question: How did Noah ("rest") managed to save living creatures of the earth in a seemingly tiny Ark?
The answer to this question lies, in my opinion, in the verses of the text.
Let's take a look at Genesis 6:19-20:
19 וּמִכָּל־הָ֠חַי מִֽכָּל־בָּשָׂ֞ר שְׁנַ֧יִם מִכֹּ֛ל תָּבִ֥יא אֶל־הַתֵּבָ֖ה לְהַחֲיֹ֣ת אִתָּ֑ךְ זָכָ֥ר וּנְקֵבָ֖ה יִֽהְיֽוּ׃
20 מֵהָע֣וֹף לְמִינֵ֗הוּ וּמִן־הַבְּהֵמָה֙ לְמִינָ֔הּ מִכֹּ֛ל רֶ֥מֶשׂ הָֽאֲדָמָ֖ה לְמִינֵ֑הוּ שְׁנַ֧יִם מִכֹּ֛ל יָבֹ֥אוּ אֵלֶ֖יךָ לְהַֽחֲיֽוֹת׃
19 And of every living thing of all flesh, two of every sort shalt thou bring into the ark, to keep them alive with thee; they shall be male and female.
20 Of fowls after their kind, and of cattle after their kind, of every creeping thing of the earth after his kind, two of every sort shall come unto thee, to keep them alive.
As you can see, even from this verse we can extract useful information. Take a look at the words "בשר" (basar) and "רמש" (remes). This means that only "flesh" was preserved, all "non-flesh" creatures (i.e. spiders, cockroaches, e.t.c) were not considered "flesh" and "moving animal" and thus were not included in the Ark. Only birds and animals (both clean and unclean) were included in the Ark. Sea animals were not included for obvious reasons. So how many were there?
The list of unclean birds and animals can be found in Leviticus 11. A rough count gives the following numbers:
1) Clean Animals - Goats, Cows, Sheep (7 each) = 7x3=21
2) Unclean Animals - Camel, Coney, Hare and Swine (2 each) = 4x2=8
3) Clean Birds - Chicken, Quails (7 each) = 2x7=14
4) Unclean Birds - Eagle, Ossifrage, Ospray, Vulture, Kite, Raven, Owl, Night-hawk, Cuckoo, and the Hawk, Little Owl, Cormorant, Great Owl, Swan, Pelican, Gier Eagle, Stork, Heron, Lapwing, and the Bat. (2 each) = 20x2=40
5) Clean Swarmers (?) - Locust, Bald Locust, Beetle and the Grasshopper (7 each) = 4x7=28
6) Unclean Swarmers - Weasel, Mouse,Tortoise, Ferret, Chameleon, Lizard, Snail and Mole (2 each) = 8x2=16
So Total of 127 living creatures were in the Ark, this is not conting Noah and his family. And since the Ark was 300x50x30 cubits (Genesis 6:15), in my opinion it was plenty to house all of these creatures and food supplies without any discomfort.
In other words, it is my opinion that the text only specifies Order or Class of the living creatures, not Family or Genus. This is why it was possible to repopulate the earth with the same diversity of the animals as there were before. I guess these particular animals carry enough genetic information to allow mutation into other animals over time. Same goes for birds - you get the idea!
What do you think?