--- title: The aquarium: jellyfish, octopuses, sea stars and the deep sea — a lesson of Mova's school · trees and pragmatics description: «The aquarium: jellyfish, octopuses, sea stars and the deep sea», a lesson of the biology course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Some of the strangest animals in the aquarium are not fish at all: jellyfish, octopuses, cuttlefish, sea st --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/) / The aquarium: jellyfish, octopuses, se… # The aquarium: jellyfish, octopuses, sea stars and the deep sea Lesson 92 of the biology course of Mova's primary school: 16 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/0/) — Some of the strangest animals in the aquarium are not fish at all: jellyfish, octopuses, cuttlefish, sea stars and lobsters have no backbone, which makes them invertebrates. - [1](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/1/) — A jellyfish pulses in its blue-lit round tank with no brain, no heart and no bones, yet it swims, catches food and grows, steered by a simple net of nerves. - [2](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/2/) — An octopus is the opposite, a clever animal with a big brain, three hearts and blue blood, and so soft that it can pour itself through a gap no bigger than its beak. - [3](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/3/) — In the dark deep-sea gallery, fish glow with their own light, because far down where sunlight never reaches, making light is the only way to be seen. - [4](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/4/) — Cartoons borrow a few true features, like Patrick's five arms in SpongeBob, and invent the rest, so a good scientist checks which parts are real. - [6](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/6/) — Jellyfish are not fish: they are relatives of corals and sea anemones, and fish have backbones, gills and fins while jellyfish have none of these. - [7](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/7/) — A small jellyfish called Turritopsis can turn back from an adult into a young stage when hurt or stressed, but it can still be eaten or fall ill, so it is not truly immortal. - [8](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/8/) — An octopus has no bones, and its beak is its only hard part, so it can squeeze through any hole bigger than the beak; octopuses have escaped from aquarium tanks. - [9](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/9/) — Octopuses can learn to unscrew jar lids, even from the inside, and their eight arms are full of nerve cells, so each arm can touch, taste and act partly on its own. - [10](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/10/) — An octopus has three hearts, two for the gills and one for the body, and its blood is blue because it uses copper instead of iron to carry oxygen. - [12](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/12/) — Cuttlefish change colour and pattern in less than a second using millions of tiny colour sacs in the skin; they seem to be colour-blind, yet they still match their backgrounds very well. - [13](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/13/) — A sea star opens a mussel by pulling with its tube feet until the mussel tires, then pushes its stomach out of its mouth into the shell. - [14](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/14/) — A sea star has no brain, can regrow a lost arm, and has a simple eye spot at the tip of each arm that senses light. - [15](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/15/) — Live lobsters are usually greenish brown and turn red only when cooked, because heat breaks down a protein that hides the red colour; a rare blue lobster, by a common estimate about one in two million, has a gene change. - [16](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/16/) — Many deep-sea animals make their own light, called bioluminescence, to find food, lure prey and signal; the anglerfish dangles a glowing lure in front of its mouth. - [17](https://md.mova.elamur.ai/free/en/corpora/school/biology/92-the-aquarium-jellyfish-octopuses-sea-stars-and-the-deep-sea/17/) — In SpongeBob, Patrick is a sea star and Squidward is named like a squid, but his creator said he is an octopus, drawn with six legs instead of eight arms; a real sea sponge, like SpongeBob's namesake, is a simple animal with no brain that filters water. - ← previous: [The aquarium: the shark tunnel and the rays](https://md.mova.elamur.ai/free/en/corpora/school/biology/91-the-aquarium-the-shark-tunnel-and-the-rays/) - next →: [The aviary: the walk-through tropical house](https://md.mova.elamur.ai/free/en/corpora/school/biology/93-the-aviary-the-walk-through-tropical-house/) - ↑ back to [Biology](https://md.mova.elamur.ai/free/en/corpora/school/biology/)