Is a worm an ectotherm

Yes, they are.I'd say endothermic because their cold blooded, so they don't give of heat...

Added: (to my best knowledge and that of my thermodynamic professor, who teached me that: ......)

ANY living cell or organism produces heat (THUS EXOthermic), that's a general thermodynamic Principle (or Law) and the only way to keep 'LIFE' living.

All reactions needed for:

1. movement
2. reproduction
3. eat and digest
4. growth
5. and even sleep (maintenance), sweat (cool down), shivering (warm up),
6. etc.

are EXOTHERMIC.

'Cold or warm blooded' for animals has something to do with its internal temperature being different from outside temperature, and sometimes the maintenance of this difference.

It says 'how' and 'what's needed' to maintain its body temperature, and nothing about processes to stay alive.