Neither tubules nor Aplysia are fish, they are marine molluscs. Microtubules and Aplysia are not the same animal. The main difference is that they have different subject classifications, different morphological characteristics, and different living habits. The details are as follows:

1. Different subject classifications

1. Microtubules

The small tube is the squid, which is an animal of the phylum Mollusca, the class Cephalopoda, and the order Decabrachia.

2. Aplysia

Aplysia, also known as sea slug, is an animal from the phylum Mollusca, class Gastropoda, and order Nudibrachia.

2. Different morphological characteristics

1. Small tubes

The body is conical, pale in color, with light brown spots, a large head, and tentacles in front of it. There are 10 fins at the end of the tail, which are triangular in shape. They often swim in groups in the ocean at a depth of about 20 meters.

2. Aplysia

The two pairs of antennae on the head of Aplysia protrude like rabbit ears, and the body is smooth or has many protrusions. The tentacles have a clear division of labor. The front pair is slightly shorter and specializes in touch; the back pair is slightly longer and specializes in smell. When Aplysia is crawling on the seabed, the pair of tentacles at the back are separated into an "eight" shape and stretched forward diagonally to sniff the surrounding smell. When resting, the pair of tentacles immediately come together and point straight upward, just like the two long ears of a rabbit.

When it is not moving, it looks like a little white rabbit squatting on the ground with a pair of big ears erect, so it was first called sea hare by the Romans. It was later recognized by the world, hence the name Aplysia.

3. Different living habits

1. Small tubes

They often move in the middle and upper layers of shallow seas, and their vertical movement range can reach more than a hundred meters. It feeds on krill, sardines, silverfish, small male fish, etc., and is itself the prey of ferocious fish. The eggs mature in batches and are laid out in batches. The eggs are wrapped in a glial ovoid. Each ovoid contains several to hundreds of eggs depending on the species. The number of eggs laid by different species also varies greatly, ranging from several hundred. to tens of thousands.

2. Aplysia

Aplysia likes to live in an environment with clear sea water, smooth water and dense seaweed, and feeds on various seaweeds. It has a very special ability to avoid enemies, that is, it turns into whatever color it eats. For example, a sea hare that eats red algae has a rose-red body, and a sea hare that eats fucus algae has a brown-green body. Some Aplysias also have villi-like and branch-like protrusions on their body surface, which makes the Aplysia's body shape, color and pattern very similar to the seaweed in its habitat, thus avoiding a lot of trouble and danger for itself.

Reference for the above content? Baidu Encyclopedia - Xiaoguan, Baidu Encyclopedia - Squid, Baidu Encyclopedia - Aplysia