It occured to me while reading the Gen 1, that reptiles may be implied by the verses.
First check out this answer. The exegetical approach used therein is the one I am attempting to use.
Next, note the wording of verse 20, when water life and flying things are introduced:
וַיֹּאמֶר אֱלֹהִים--יִשְׁרְצוּ הַמַּיִם, שֶׁרֶץ נֶפֶשׁ חַיָּה; וְעוֹף יְעוֹפֵף עַל-הָאָרֶץ, עַל-פְּנֵי רְקִיעַ הַשָּׁמָיִם.
And God said: 'Let the waters swarm with swarms of living creatures, and let fowl fly above the earth in the open firmament of heaven.'
And then in verse 21:
וַיִּבְרָא אֱלֹהִים, אֶת-הַתַּנִּינִם הַגְּדֹלִים; וְאֵת כָּל-נֶפֶשׁ הַחַיָּה הָרֹמֶשֶׂת אֲשֶׁר שָׁרְצוּ הַמַּיִם לְמִינֵהֶם, וְאֵת כָּל-עוֹף כָּנָף לְמִינֵהוּ, וַיַּרְא אֱלֹהִים, כִּי-טוֹב.
And God created the great sea-monsters, and every living creature that creepeth/ moveth, that the waters swarmed, after its kind, and every winged fowl after its kind; and God saw that it was good.
The creeping things were not mentioned from the outset. This is as opposed to day 6:
וַיֹּאמֶר אֱלֹהִים, תּוֹצֵא הָאָרֶץ נֶפֶשׁ חַיָּה לְמִינָהּ, בְּהֵמָה וָרֶמֶשׂ וְחַיְתוֹ-אֶרֶץ, לְמִינָהּ; וַיְהִי-כֵן.
And God said: 'Let the earth bring forth the living creature after its kind, cattle, and creeping thing, and beast of the earth after its kind.' And it was so.
וַיַּעַשׂ אֱלֹהִים אֶת-חַיַּת הָאָרֶץ לְמִינָהּ, וְאֶת-הַבְּהֵמָה לְמִינָהּ, וְאֵת כָּל-רֶמֶשׂ הָאֲדָמָה, לְמִינֵהוּ; וַיַּרְא אֱלֹהִים, כִּי-טוֹב.
And God made the beast of the earth after its kind, and the cattle after their kind, and every thing that creepeth upon the ground after its kind; and God saw that it was good
also note a distinctive pazer mark above הָרֹמֶשֶׂת, which separates the phrase "and all the creeping things" From "That the waters swarmed".
Verse 21 could very well have read as follows:
וַיִּבְרָא אֱלֹהִים, אֶת-הַתַּנִּינִם הַגְּדֹלִים; וְאֵת אֲשֶׁר שָׁרְצוּ הַמַּיִם לְמִינֵהֶם, וְאֵת כָּל-עוֹף כָּנָף לְמִינֵהוּ, וַיַּרְא אֱלֹהִים, כִּי-טוֹב.
And God created the great sea-monsters, and that which the waters brought forth, after its kind, and every winged fowl after its kind; and God saw that it was good.
שרצו is translated by Onkelos as ארחישו, which can mean to bring forth, (look it up!)
Thus I assert that the phrase וְאֵת כָּל-נֶפֶשׁ הַחַיָּה הָרֹמֶשֶׂת, refers to other crawling things, those that came most directly from water, (hence the juxtaposition), namely land reptiles.
And should you say, let the verse say "and that which the waters brought forth", here the verse tells of the actual creation of water life. By the actual creation of land creatures, (verse 25). it also mentions רמש and it is separate from other types of animals. Just as it is separate there, it is separate here.
Also, note the phrase נֶפֶשׁ הַחַיָּה, living creature, that is used in verse 20 and 24, when introducing new life forms. This same phrase is present in verse 21, on our creeping things, suggesting a new distinct life form. see verse 25 on day where the phrase is not used when the creative process is described. Just as those refer to new life forms, so does this.
The obvious question, of course, is why crawling things are mentioned both on day 5 and on day 6. To that question I would say that there are indeed many crawling things, such as rodents or insects, that are in a different category of crawling things than land reptiles, (land reptiles being more closely related to amphibians and to water life), that are meant by the mention on day 6.
The verse, even read simply, as is, could imply that the water brought forth crawling things that crawled on the land. Note that birds are mentioned last by the verse.
The the verse would mean:
And God created the great sea-monsters, and every living creature that creepeth, that the waters brought forth, (meaning both things that are still in the water, and things that went on to the land, directly from water), after its kind, and every winged fowl after its kind; and God saw that it was good.
So perhaps we can say that the verse alludes to crawling things that came forth from the water and became birds, land reptiles.
Lastly, I think it is poignant that God blesses water life on day 5, but not life on day 6. See verse 22. The next blessing is given to man in verse 28. Is land life not blessed?
Perhaps we can say that Land life, and in fact all life, originating from water, (except plants), was already blessed by God, in verse 22, so further blessing would have been redundant.
And one last thought, the name of the cantillation mark I mentioned above, the pazer, פזר, means disperse, which perhaps hints at a dispersal of species from water!
Dr. Schroeder, Rabbi Slifkin, and a baby seal?! :D