Some arthropods can produce a smelly odor like a carabid beetle or some millipedes. Some will bleed a toxic blood to destroy their enemies.
How do they defend them selves??
the structures of defense can be their claws and sharp teeth
Most do not, but some will produce a foul odor in self defense.
Stinging cells
many minds
It's neck
Aquatic arthropods typically exchange gases through gills. Gills are structures that are rich in blood vessels and provide a large surface area for gas exchange to occur, allowing the arthropods to extract oxygen from the water and release carbon dioxide.
no arthropods have endoskeletons, completely different structures nothing like exoskeletons, exoskeletons are outer skeletons made of chitin only found on arthropods, endoskeletons are inner support structures like your skeleton, made of bone and/or cartilage.
Malpighian tubules are the structures that help arthropods maintain water balance. These tubules are responsible for removing waste and regulating the concentration of solutes in the hemolymph, helping to conserve water in arthropods' bodies.
Most aquatic arthropods reproduce by laying eggs. These eggs can be deposited on structures in the water or carried by the female until they hatch. Some aquatic arthropods also undergo complex mating rituals or behaviors before reproducing.
Certainly. Arthropods include insects, which have six legs, and arachnids which have eight legs, and crustaceans which have various numbers of legs, but they do all have legs, and they use them to move around. That is al lfor know
Lionfish have poisonous spines.