Which statement best explains why invertebrates often have outer skeletons but vertebrates do not?
The outer skeleton provides protection, since invertebrates do not have backbones.
The outer skeleton surrounds the spinal cord, since invertebrates do not have backbones.
The outer skeleton helps invertebrates maintain homeostasis, since they lack spinal cords.
The outer skeleton helps invertebrates maintain homeostasis, since they lack membrane-bound organelles.

The outer skeleton provides protection, since invertebrates do not have backbones

Explanation:

The spinal cord (backbone) contributes to the body's protection. Using the human body as a case study, the backbone protects the body as it supports all skeletal structure of the body. But to cover up for that in most invertebrates, they need an outer steleton for protection from damage due to movement and dangerous foreign chemicals.

ecological efficiency: % of usable energy transferred as

biomass from one trophic level to the next typical is 10% efficient (90% of

energy is lost),is diagramed as the pyramid of energy flow. then osprey eagle

are tertiary consumer and the shrimp are primary consumer, so to balance

mass of shrimp (1/0.1) / 0.1 = 100 kg 

the answer is :