Pacific Gooseberry, Pleurobrachia bachei

Pacific Gooseberry, Pleurobrachia bachei. Zooanthellae photographed in its native environment off Isla Carmen within the Bahía de Loreto National Park, Baja California Sur, March 2025. Photograph and identification courtesy of Dr. Jake Turin, Albuquerque, New Mexico.

Phylogeny:  The Pacific Gooseberry, Pleurobrachia bachei (Agassiz, 1860, is a member of the Cydippida Family of Comb Jellies and Ctenophora Phylum. They are known as a jelly but they are not true jellyfish. Their mitochondrial genome consists of only twelve genes. The Pleurobrachia Genus is one of thirteen in the Cydippida Family, and there is only this species in the Cydippida Genus. They are also known as the Cat’s Eye Comb Jelly, the Pacific Sea Gooseberry and the Sea Walnut and in Mexico as Grosella Marina.

Morphology: The Pacific Gooseberry has a small, globular, body that is composed of 99% water with a biradial symmetry in a typical comb jellyfish shape that is nearly spherical with eight evenly spaced comb rows (cilia) evenly spaced extending across the entire circumference, that consist of thousands of fused macrocilia controlled by an apical organ, and two long tentacles. The tentacles have smaller tentillumwhich makes them resemble a feather when fully extended. They are transparent with the cilia refracting the light to produce a rainbow-like colors, that give the false appearance of bioluminescence. The branched tentacles can be white, yellow, pink or orange. Their body length reaches a maximum of 2.0 cm (0.8 inches) in length; their two tentacles can reach a maximum of 15.0 cm (5.9 inches) in length. They utilize their cilia for locomotion and are the largest animals in the world to move through the use of cilia. They are incapable of producing light and they lack stinging cells.

Habitat and Distribution: The Pacific Gooseberry is pelagic that lack any sessile stages and are wholly planktonic in their life cycle.  They are found in marine environments normally within 5.0 km (2.0 miles) of shore at depths up to 50 m (165 feet). They can be found in large numbers in protected coastal bays and are normally found within the first 15 m (50 feet) during the day. They are frequently found washed up on beaches. The Pacific Gooseberry is found in all Mexican coastal waters of the Pacific Ocean with the exception that they are absent from south of Acapulco, Guerrero, along the southwest coast of the mainland. They are often confused with medusoid Cnidaria which are jellyfish with bell shapes that contain stinging cells.

Diet: The diet of the Pacific Gooseberry consists of copepods, eggs, larval fish, mollusks, and other tiny organisms. They utilize their tentacles, which possess sticking cells (colloblasts), to ensnare prey and pull food into their mouths. When hunting the long tentacles are extended and dragged behind. In turn they are preyed upon by large jellyfish, fishes and sea turtles.

Reproduction:  The Pacific Gooseberry is a self-fertilizing hermaphrodite that reproduces sexually. Fertilization takes place externally and the resulting larvae are free swimming without parental care. They die after spawning. The Sea Gooseberry is planktonic its entire life, and there is no sessile stage. Once a larva has become a fully grown gooseberry, it is capable of releasing up to 1,000 eggs per day with gametes being released into the ocean via the gonopores, located on the comb-rows. They have lifespans of between four and six months.

Conservation: From a conservation perspective the Pacific Gooseberry has not been formally evaluated. However they are fairly common with a wide distribution and should be considered to be of Least Concern. They are believed to play an important role in helping to balance the ecosystem keeping copepod populations in check. In namesake they are often confused with Gooseberries which are plants of the Ribes Genus.

Synonyms:  None.