Animal evolution is often presented as a march toward complexity, with different living
animal groups each representing grades of organization that arose through the progressive …

Neurons are defined as polarized secretory cells specializing in directional propagation of
electrical signals leading to the release of extracellular messengers–features that enable …

A hallmark of metazoan evolution is the emergence of genomic mechanisms that implement
cell-type-specific functions. However, the evolution of metazoan cell types and their …

Introduction An understanding of ctenophore biology is critical for reconstructing events that
occurred early in animal evolution. The phylogenetic relationship of ctenophores (comb …

Eye evolution is driven by the evolution of visually guided behavior. Accumulation of
gradually more demanding behaviors have continuously increased the performance …

Cnidarians are astonishingly diverse in body form and lifestyle, including the presence of a
jellyfish stage in medusozoans and its absence in anthozoans. Here, we sequence the …

Fireflies and their luminous courtships have inspired centuries of scientific study. Today
firefly luciferase is widely used in biotechnology, but the evolutionary origin of …

The opsin gene family encodes key proteins animals use to sense light and has expanded
dramatically as it originated early in animal evolution. Understanding the origins of opsin …

Genomic and transcriptomic analyses show that sponges possess a large repertoire of
genes associated with neuronal processes in other animals, but what is the evidence these …

Here we review the examples of great longevity and potential immortality in the earliest
animal types and contrast and compare these to humans and other higher animals. We start …