Berghia Nudibranch Lifecycle

Berghia Nudibranchs (Aeolidiella stephanieae) spend their entire life eating aiptasia, sleeping, mating, laying egg strings, and producing more Berghia Nudibranchs, and that is it!

Berghia Nudibranchs are “hermaphrodites,” which means that a single nudibranch has both male and female sexual reproductive organs on its body; however, they do require two in order to mate, and both can leave the mating ritual with fertilized egg strings!

Eggstrings are laid in a circular spiral on rocks (usually on the underside of live rocks) and on the glass in the home aquarium. Hatching occurs in about 11 to 12 days (at a temperature of about 75F or 24C).

The unique thing about the Berghia is; depending on dissolved oxygen content, a percentage of the larvae will emerge as free swimming (planktonic) while the other percentage will metamorphisize (skipping the planktonic stage, this is called poecilogonous development) and emerge as juveniles, complete with a foot; both from the same eggstring!

Berghia Larvae And Juveniles Emerging

Juvenile Berghia begins to feed on aiptasia (Aiptasia pallida) approximately 3 to 4 days after metamorphosis occurs. Juveniles that are four days old can be challenging to see with the naked eye, measuring about 120 microns! Once the juveniles emerge, they eat aiptasia at an unbelievable rate and can double their body mass in just a few days. (A well-fed young adult measuring 1/4″ can grow to a length of 1/2″ in about 1 to 2 weeks!)

Adult And Young Adult Berghia

Young adult Berghia Nudibranchs reach sexual maturity approximately 47 days after the egg strings are laid and can lay egg strings themselves! This means more Berghia Nudibranchs to tackle your aiptasia problem! As they are growing, they can double their body mass in a single week or two!

Berghia Nudibranchs (Aeolidiella stephanieae) can grow to a size of 1 1/2″ to a full 2″ and have an average lifespan of about 6 to 8 months. During their life span, they will eat hundreds of aiptasia and lay thousands of eggs!

Will the real Berghia please stand up?

The aiptasia eating nudibranch known in the aquarium industry as Berghia (Berghia verrucicornis) is not actually that species; the nudibranch used in the aquarium industry for aiptasia control was named and classed in 2005 (see the article here at the Sea Slug Forum) as Aeolidiella stephanieae. This is the nudibranch that Stephen Kempf did so much work with under the name Berghia verrucicornis.

Since this nudibranch has been misnamed in the aquarium trade for so long and is now commonly known to hobbyists as Berghia, the name Berghia will probably remain; however, Berghia are not Berghia at all…they are Aeolidiella stephanieae. Our nudibranchs are the true Aeolidiella stephanieae!

An Incredible Sense Of Smell, The Rhinophores Of A Berghia

The “antenna-like” appendages on the head of the Berghia Nudibranch (Aeolidiella stephanieae) are called rhinophores and are used to “smell” the water column to quickly find food and one another. When a Berghia has located food, they curl back the rhinophores on the top of the head to help protect them from the tentacles of the aiptasia.

As they approach the base of the aiptasia, they use the rhinophores around their mouth (known as oral rhinophores) to determine the size of the aiptasia; they also use their oral rhinophores to gently “tap” the base of the aiptasia to get the aiptasia to contract its tentacles so that they can move in for the kill.