Which organism is described as non-insect and ametabolous?

The organism described as non-insect and ametabolous is a centipede. Ametabolous organisms do not undergo metamorphosis, meaning they do not have distinct larval, pupal, and adult stages like insects do. Instead, ametabolous organisms develop directly into adulthood, growing in size without significant morphological changes, only shedding their exoskeleton as they grow.

Centipedes belong to the class Chilopoda, which is part of the phylum Arthropoda but distinctly separate from insects. They possess an elongated body, segmented with one pair of legs per segment, and are predatory, primarily hunting other small invertebrates. In contrast to the centipede, the other options are insects, each with distinct life stages that include metamorphosis.