What Animal Improvements Can a Simic Hybrid Druid Keep on Wild Shaped?

What Animal Improvements Can a Simic Hybrid Druid Keep on Wild Shaped?
Manta Glide, nimble climber, underwater adaptation, lifting attachment, carapace and / or acid spit?

Does the type of beast that I am working on Wild Shape determine, if I can keep a certain animal improvement? For example, if I wanted to make a wild crab, would I keep my trailer attachment feature? What if I wildly turn into a bear?