Why are there no large-sized arthropods, like the size of a cow? Thank you?

Answer 1

Arthropod size is limited by the way they breath. Instead of having lungs they have tubes called trachea which start at many points on the outside of their bodies and then continually branch inside the bodies delivering air to every part. Because there is no active way to draw air into the body this mode is limited by the amount of oxygen in the air and the size of the organism. The larger the arthropod the less gas exchange can occur due to the air not being able to make it up inside the trachea by diffusion alone.

Answer 2

Its also a function of the limbs ability to support the arthropods weight, especially terrestrial species......some marine arthropods for this reason can grow to large sizes eg King Crabs which are buoyed by the water.

Answer 3

You've never been to New Jersey? You should see the mosquitos here!!!!
Just kidding ...

agreed ...the open circulatory system limits the size of the arthropod.

Answer 4

also because the exoskeleton of an arthropod cannot grow as the animal grows, so they tend to be smaller creatures.

Answer 5

It's just not practical. they have open circulatory systems (which are only effective in small animals) and respiratory systems that generally absorb oxygen through the skin. (the most impractical of the two reasons is the open circulatory system)