I'm sorry, but nothing observed in biology MUST have been intelligently designed. To claim such, you must first define a criteria for intelligent design, and no such criteria exists. It has basically come down to, "I can't figure out how this may have evolved naturally, so it must be intelligently designed." This is basing a movement on NEGATIVE evidence, when it needs to be based on POSITIVE evidence to be considered science. In other words, you have to find something to support your position, not something that undermines someone else's.
Junior, don't get all hung up on the word MUST. In science, many, many things are taught where the the odds point to a MOST LIKELY scenario. And that is ID. So, don't even attempt to pull that lame straw man out of your bag of tricks.