Question

Why are spiders considered as saprophytic ??

Answer 1

I guess it depends on what definitions one chooses. The term "saprophytic" is not used much anymore but generally refers to the ingestion of dead or decaying organic matter. By this definition, scavengers are saprophytes, which may be one of the reasons why the term is no longer commonly used. Spiders usually either secrete or inject digestive enzymes onto or into their prey and then suck up the digested organic matter. So saprophytic could apply to this mode of nutrition. Holozoic nutrition usually refers to the ingestion of solid organic matter, which spiders tend not to do. Some definitions of holozoic, though, include the ingestion of liquid organic matter, which would apply to spiders.

Answer 2

Spiders are considered as saprophytes because they feed upon dead and decayed organisms.

Explanation:

Each and every living organism has different modes of nutrition. The plants are called autotrophs as they have the ability to prepare their own food. Apart from the plant, all other living organisms are called Heterotrophs. The Heterotrophs are further classified as saprophytes, parasites, lichens, etc.  

Saprophytes are those organisms which derive its nutrition form feeding on the dead and decaying organism. Spider either feeds upon live insects or sometimes dead ones. This it is called as saprophytes.