Were land-dwelling vertebrates the only organisms preserved on the Ark?

Genesis gives the impression that the animals preserved from the Flood of Noah's time were mostly, or entirely, land vertebrates -- mammals, birds, and land-living reptiles and amphibians, although it doesn't explicitly say this:
Genesis 7:1 Yahweh said to Noah, “Come with all of your household into the ship, for I have seen your righteousness before me in this generation. 7:2 You shall take seven pairs of every clean animal with you, the male and his female. Of the animals that are not clean, take two, the male and his female. 7:3 Also of the birds of the sky, seven and seven, male and female, to keep seed alive on the surface of all the earth. 7:4 In seven days, I will cause it to rain on the earth for forty days and forty nights. Every living thing that I have made, I will destroy from the surface of the ground.” (World English Bible, public domain)

Leviticus 11:20 “‘All flying insects that walk on all fours are an abomination to you. 21 Yet you may eat these: of all winged creeping things that go on all fours, which have legs above their feet, with which to hop on the earth. 22 Even of these you may eat: any kind of locust, any kind of katydid, any kind of cricket, and any kind of grasshopper. 23 But all winged creeping things which have four feet, are an abomination to you.
This passage from Leviticus may indicate that Arthropods (insects, spiders, and more) were classified, by God, as clean or unclean, just as mammals and birds are. That doesn't prove that, say, butterflies and centipedes were on the Ark, but it is possible.

Some questions come to mind. (In 2007, I posted a series of questions about Noah's Flood. There is some repetition with the previous post in the current one, but the two are significantly different.) The questions here are related to the variety and care of the animals on the Ark.

1) Does the Bible really describe a world-wide flood? Others have considered this, and there are plenty of opinions available, so I won't attempt to answer this, except to say that there seem to be these possibilities:
a) there was a world-wide flood.
b) there was a localized flood, but it was experienced by ancestral humans, who thought it was world-wide, or described it as if it were. (perhaps they were living in a large basin, which became the Mediterranean Sea after the flood.) See here for a discussion by theologians who believe that there was an important flood, but that it was not actually world-wide. Here is a discussion of the literary genre of Genesis 1-11. At least some important early theologians did not take Genesis 1-11 to be strictly historical.
c) The entire story of Noah and the Flood is a parable, or just a story, in the Bible to emphasize the dangers of evil living, and God's care for His creation.

Added May 19, 2020:
Here's a post from a Christian geologist who believes that there really was a flood in Noah's time, but does not believe that the Bible really teaches that it was world-wide. He also does not believe that that flood was responsible for as many geological phenomena as many Young-Earth creationists claim that it was.

2) If there was a world-wide flood, how did animals from, say, New Guinea, get to the Middle East, in order to get in the Ark, and, if they did, how did they get back to their origin, without leaving evidence of their passing through, including offspring and fossils, behind them? Joel Duff has considered this question in depth for armadillos and their relatives.
3) How were pairs of unclean animals selected? I have done some bird sexing, and, although, in many cases, it is easy to distinguish males from females, in some cases, it isn't, and the same would be true of many reptiles and amphibians, and even some mammals. Did the animals come marching, or slithering, or hopping, or flying, into the Ark in pairs by Divine impulse of some kind? Genesis seems to indicate that Noah was to do the selecting. {"you shall take with you")
4) Some mammals, such as anteaters, have insects as their diet. Was it necessary to have not just a pair, but, say, an entire termite nest, on the Ark, for the feeding of such mammals? That would be far more than a pair, or seven, of termites.
5) Some bees, ants, some wasps, termites, mole rats, and other animals are eusocial. Would a pair, or seven of these, be able to survive? For example, honeybees would presumably need a queen, a drone, and workers of more than one type.
6) Many animals eat living, fresh plant material, such as pollen, nectar, leaves, or fruit. Would the Ark have needed a bamboo grove for giant pandas, or a field of flowering plants for bees and butterflies? Living plants require sunlight for photosynthesis, leading to growth. Would the ark have had provision for lighted plants? The diets of some animals (like pandas) is restricted to a single type, or very few plants, and it is difficult to see how conditions on the ark could have been able to support all of the different types of plants needed by the variety of animals. Answers in Genesis has considered these questions. Basically, their claim is that the animals on the ark were not specialized as to diet.
7) Many salt-water organisms don't do well if suddenly immersed in fresh water, or are unable to survive in fresh water at all. The reverse is also true. (See here.) Presumably the flood, if there was a world-wide one, was of fresh water. Either the oceans of Noah's day were fresh, or marine organisms of that time were much better able to survive sudden immersion in fresh water than most current organisms.
8) How could there have been room for all the types of animals? Answers in Genesis has considered that question, and their belief is that there were less than 150 types of animals on the Ark, and that all of the variety of land animals now in existence evolved (although they don't use that word much) from these. I find such a proposal impossible to believe. (So do others!) There's no fossil, traditional or artistic evidence for such rapid changes and diversification in animal form and behavior -- lions seem to have been lions for at least the past few thousand years for example. If this rapid evolution occurred after the Ark landed, why didn't it occur between Adam's time and Noah's, so that there would have been much more than 150 kinds by Noah's time? See here for a fuller discussion.
9) If there was a world-wide flood, how were land-living invertebrates, such as snails, insects, centipedes, spiders, annelid worms, and more, stored, fed, and protected? (See question 6, above.)
10) If there was a world-wide flood, why is there little or no geological evidence for this?

Thanks for reading.