Ricardo marveled at how the jellyfish squeezed the complexity of vision and orientation into tiny rhopalia only about two hundredths of an inch long.

You, like Ricardo Sztein, the protagonist of Jellyfish Have Eyes, may be fascinated by jellyfish for many reasons. Maybe it’s the fact that these organisms aren’t fish and aren’t enticing like jelly or jam. Whatever draws you to explore the wondrous world of these ancient Cnidarians, Joram and Ricardo hope you enjoy the resources on this page, and invited you to add more in the comments section below.

Anatomy of a jellyfish by Zina Deretsky, National Science Foundation. Click the image to see a larger version.

Anatomy of a jellyfish by Zina Deretsky, National Science Foundation. Click the image to view the Wikipedia page with original of this image.

For Kids of All Ages

Recent Research That Caught Our Eyes

Photo of Moon Jellyfish in captivity

An adult Aurelia aurita or Moon Jelly. Because of the lighting, the organism in shown in false color. Photo by Hans Hillewaert.

Jellyfish Able to Achieve Self-Repairing Symmetry

Scientists studying animals with the capacity to self-repair injuries are taking a closer look at jellyfish. The study found that the moon jellyfish Aurelia aurita rearranges existing body parts and recovers radial symmetry within a few days after losing an arm [Watch the Video of the moon jellyfish self-repairing.]. The rearrangement of body parts requires the jellyfish to rebuild their muscular networks and recenter their manubria, the stalk like structure which connects with the mouth and anus. Read the report.

Jellyfish Swim Against the Tide of Expectations

A recent study concludes Jellyfish don’t float aimlessly through their long lives. The study equipped wild Rhizostoma with accelerometers, which provided data that seems to indicate “jellyfish can orientate their movements with respect to currents” and that “They can actively swim countercurrent in response to current drift.” This adaptive behavior is believed to contribute to the swarm or bloom’s survival. Read the full report, “Current-Oriented Swimming by Jellyfish and Its Role in Bloom Maintenance” in Current Biology.

Figure 1. Cubozoan visual system. The visual system of the cubozoan Tripedalia cystophora (A) comprises four sensory structures called rhopalia (B). Each rhopalium carries six eyes of four morphological types (lower lens eye LLE, upper lens eye ULE, pit eye PE and slit eye SE) and a light sensitive neuropil (NP, red broken line). The eyes are responsible for the image formation in the animal and the light sensitive neuropil is thought to be involved in diurnal activity.

Figure 1. Cubozoan visual system.
The visual system of the cubozoan Tripedalia cystophora (A) comprises four sensory structures called rhopalia (B). Each rhopalium carries six eyes of four morphological types (lower lens eye LLE, upper lens eye ULE, pit eye PE and slit eye SE) and a light sensitive neuropil (NP, red broken line). The eyes are responsible for the image formation in the animal and the light sensitive neuropil is thought to be involved in diurnal activity.

Jellyfish Study Sheds Light on the Eyes
New study explores the the molecular basis of light sensitivity in the Jellyfish. Read the full report: Ocular and Extraocular Expression of Opsins in the Rhopalium of Tripedalia cystophora (Cnidaria: Cubozoa)