A seal is (heavy) a seahorse
heavier than
A jellyfish is (big) an octopus
bigger than
A squid is (long) a crab
longer than
A seahorse is (small) a seal
smaller than
A turtle is (slow)
slower than
A crab is (ugly) a seahorse
uglier than
An octopus is (colourful) a shark
more colourful
A dolphin is (fast) a fish
faster than
A whale is (pretty) an octopus
prettier than
A shark is (dangerous) a crab
more dangerous