"Male and female they shall be" (Genesis 6:19). If you see a male running after a female, accept it; but if a female runs after a male, do not accept it. This works well for Rabbi Yohanan, who said that no flood came down upon the Land of Israel, so the reem could stand there. But according to Resh Lakish, where did the reem stand? Rabbi Yannai said: they brought the young of the reem into the ark. But did not Rabbah bar bar Hannah say, "I myself saw a day-old reem calf, and it was like Mount Tabor; and how large is Mount Tabor? Forty parsangs. The length of its neck was three parsangs, the resting place of its head a parsang and a half. It cast its dung and dammed up the Jordan." Rabbi Yohanan said: they brought its head into the ark. But you just said the resting place of its head was a parsang and a half! Rather, they brought its nostril into the ark. But did not Rabbi Yohanan say no flood came down on the Land of Israel? He said this according to the view of Resh Lakish. [But the ark was traveling about!] They tied its horns to the ark. But did not Rav Hisda say the generation of the flood sinned with boiling heat and were judged with boiling waters [which would have scorched it]? By your own reasoning, how did the ark itself travel, and how did Og king of Bashan survive? Rather, a miracle occurred and the sides of the ark cooled (Zevahim 113b). Rabbi Eleazar said: from where do we learn that an animal missing a limb is forbidden to the children of Noah? As it is said, "and of every living thing, of all flesh" - the Torah said: bring an animal whose limb-ends are alive [intact]. But this is needed to exclude a torn animal! A torn animal is derived from "to keep seed alive" (Genesis 7:3). This works for the one who says a torn animal cannot give birth; but for the one who says a torn animal does give birth, what can be said? Scripture says "with you" (Genesis 6:18) - meaning ones like you. But perhaps Noah himself was a torn one? "Blameless" is written of him. But perhaps blameless in his ways? "Righteous" is written of him. But perhaps blameless in his ways and righteous in his deeds, yet still flawed in body? That cannot enter your mind, for if Noah were a torn one, the Merciful One would have said to him, "Bring in ones like you," and whole ones he would not bring in. And now that we derive the matter from "with you," why do I need "to keep seed alive"? Had it come only from "with you," I would have said it was merely for company, even a sterile one; therefore the Merciful One wrote "to keep seed alive."
How the Giant Reem Survived the Flood
Yalkut Shimoni on Torah 55:1
זָכָר וּנְקֵבָה יִהְיוּ. אִם רָאִיתָ זָכָר רָץ אַחַר נְקֵבָה קַבְּלֵהוּ וְאִם נְקֵבָה רָצָה אַחַר זָכָר אַל תְּקַבְּלֵהוּ. בִּשְׁלָמָא לְרַבִּי יוֹחָנָן דְּאָמַר לֹא יָרַד מַבּוּל לְאֶרֶץ יִשְׂרָאֵל הָיְינוּ דְּקָם רִימָא הָתָם אֶלָּא לְרֵישׁ לָקִישׁ הֵיכָא קָם רִימָא. אָמַר רַבִּי יַנַּאי, גּוּרְאוֹת הָרְאֵם הִכְנִיסוּ לְתוֹכָהּ. וְהָאָמַר רַבָּה בַּר בַּר חַנָה, לְדִידִי חָזֵי לִי אוּרְזִילָא דְרִימָא בַּר יוֹמָא וַהֲוֵי כְּהַר תָּבוֹר, וְהַר תָּבוֹר כַּמָּה הָוֵי, אַרְבָּעִים פַּרְסָה, מַשְׁכָא דְצַוָוארֵיה תְּלָתָא פַּרְסָה בֵּי מְרַבַּעְתָּא דְרֵישֵׁיהּ פַּרְסָה וּפַלְגָא רָמָא כַּכָּא, סַכְרֵיהּ לְיַרְדְּנָא אָמַר רַבִּי יוֹחָנָן, רֹאשׁוֹ הִכְנִיסוּ לַתֵּיבָה. סוֹף סוֹף הָא אָמַרְתָּ בֵּי מְרַבַּעְתָּא דְרֵישֵׁיהּ פַּרְסָה וּפַלְגָא, אֶלָּא חָטְמוֹ הִכְנִיסוּ לַתֵּיבָה וְהָאָמַר רַבִּי יוֹחָנָן לֹא יָרַד מַבּוּל לְאֶרֶץ יִשְׂרָאֵל. לִדְבָרָיו דְרֵישׁ לָקִישׁ קָאָמַר. [וְהָא קָסַגְיָא תֵּיבָה], קַרְנָיו קָשְׁרוּ לַתֵּיבָה. וְהָאָמַר רַב חִסְדָּא בְּנֵי דּוֹר הַמַּבּוּל בְּרוֹתְחִין קִלְקְלוּ וּבְרוֹתְחִין נִדּוֹנוּ וּלְטַעַמֵיךְ תֵּיבָה הֵיכִי סַגְיָא עוֹג מֶלֶךְ הַבָּשָׁן הֵיכִי קָם, אֶלָּא נֵס נַעֲשָׂה וְנִצְטַנְנוּ צִדֵּי הַתֵּיבָה (זבחים קיג, ב). אָמַר רַבִּי אֶלְעָזָר, מִנַּיִן לִמְחוּסָר אֵבָר שֶׁאָסוּר לִבְנֵי נֹחַ שֶׁנֶּאֱמַר וּמִכָּל הָחַי מִכָּל בָּשָׂר אָמְרָה תּוֹרָה הָבֵא בְּהֵמָה שֶׁחַיִּין רָאשֵׁי אֵבָרִים שֶׁלָּהּ. הַאי מִיבָּעְיָא לֵיהּ לִמְעוּטֵי טְרֵפָה, טְרֵפָה (בראשית ז, ג) מִ"לְּחַיּוֹת זֶרַע" נָפְקָא. הָנִיחָא לְמָאן דְּאָמַר טְרֵפָה אֵינָהּ יוֹלֶדֶת, אֶלָּא לְמָאן דְּאָמַר טְרֵפָה יוֹלֶדֶת, מַאי אִיכָּא לְמֵימָר. אָמַר קְרָא אִתָּךְ בְּדוֹמִין לָךְ. וְדִילְמָא נֹחַ גּוּפֵיהּ טְרֵפָה הֲוָה, "תָּמִים" כְּתִיב בֵּיהּ. וְדִילְמָא תָּמִים בִּדְרָכָיו (שם) "צַדִּיק" כְּתִיב בֵּיהּ. וְדִילְמָא תָּמִים בִּדְרָכָיו וְצַדִּיק בְּמַעֲשָׂיו לֹא סַלְקָא דַּעֲתָךְ, דְּאִי סַלְקָא דַּעְתָךְ נֹחַ טְרֵפָה הֲוָה, אָמַר לֵיהּ רַחֲמָנָא דִכַוָותָךְ עֲיֵיל, שְׁלֵמִים לָא תְּעֲיֵיל וְהַשְׁתָּא דְּנָפְקָא לֵיהּ מֵאִתָּךְ, "לְחַיּוֹת זֶרַע" לָמָּה לִי, אִי מֵאִתָּךְ הֲוָה אֲמִינָא לְצַוְותָא בְּעַלְמָא וַאֲפִילּוּ סָרִיס, כָּתַב רַחֲמָנָא "לְחַיּוֹת זֶרַע".