Alexandraster inflatus Fisher, 1906 Poraniopsis inflata, the spiny sea star, is a species of starfish in the family Poraniidae.

It is native to the Pacific Ocean and is found in deep water off the coast of North America.

Poraniopsis inflata has a somewhat inflated body and five short arms and grows to a diameter of about 16 centimetres (6.3 in).

The aboral surface bears a moderate number of short conical spines with white tips.

It is an uncommon species and is found on rocky substrates in deep water in the Monterey region.