*rugenius in nature , 01:20

Breeding Jellyfish at the Horniman Aquarium- 05.29.12

mainjelly.jpg The latest dose of natural inspiration from our resident zoologist and London-based editor, Justine Aw.

In addition to showcasing beautiful displays, the staff of the aquarium at the Horniman Museum and Gardens also conduct fascinating research into the species in their collection, including coral reef diseases and embryonic development. The team have shared some gorgeous photos from their research into the breeding of Moon jellyfish (Aurelia aurita) with us and they provide a beautiful insight into this very complicated life cycle! More photos of the beautiful and otherworldly looking phases of developing jellies on the next page.

Jellyfish as we typically see them, are quite seasonal creatures, typically appearing in UK waters around March and disappearing by about October. They have incredibly complex life cycles, involving many stages that look nothing like the medusas we associate with them! The aquarium team at the Horniman have been doing pioneering work into the breeding and development of Moon jellies and we’re lucky to be able to share some of their amazing images (many thanks to Jamie Craggs and James Robson of the the Horniman Museum and Gardens). The original paper can be found in “Observations of the life cycle of the scyphozoan jellyfish Aurelia aurita at the Horniman Museum Aquarium”*.

diagram.png

The rather complex life cycle of the jellyfish! The sexually mature medusa (the jellies we’re used to seeing) (a) releases free swimming pill-shaped planula larvae (b), which then settle on the benthic floor as hydra-like benthic scyphistoma (c), which continue to develop, forming strobula (d), a state in which they remain until an environmental trigger causes them to turn into free swimming wagon-wheel-esque ephyrae (e), which ultimatley become our familiar medusas (f)! The medusas we see live about seven months in captivity, and the developmental phases from fertilization to strobula typically takes about three weeks. However, they remain as strobula until the environment triggers them to become free swimming.

Starting from the very beginning, although male and female jellyfish look quite similar, it is possible to tell them apart on closer inspection. Look carefully at the four ‘rings’ on these two specimens. The inside of these rings is for digestion and the outer edge is the reproductive organs.

jellyfish-dev-1.jpg

Female (left) and male (right), Moon jellyfish (Aurelia aurita). The females have less dense gonad tissue and you can see through the folds of the ovaries, whereas the tissue on the outside of those rings of the male, on the right, are more opaque.

jellyfish-dev-2.jpg

A closer look at the denser gonadal tissue of the male.

jellyfish-dev-12.jpg

Close up of developed spermatophore with spermatocytes.

jellyfish-dev-11.jpg

Close up of ovaries with oocytes.

Fertilization beings with males producing spermatozoa in mucous strings, which are collected by the female using her oral arms. Fertilization leads to the formation of planula larvae by gastrulation in and on their way to the brood pouches of the oral arms.

jellyfish-dev-3.jpg

Mature females have brood pouches along the oral arms in which the developing planula larvae develop. The larvae take on a more intense color as they develop.

jellyfish-dev-4.jpg

jellyfish-dev-5.jpg

Here is a close up of one of those brood pouches, where you can see the pill-shaped planula larvae almost ready to be released.

jellyfish-dev-9.jpg

Developed free-swimming planulae exit the pouches and enter the water column, searching for substratum on which to attach. This is a planula with nematocysts discharged.

jellyfish-dev-7b.jpg

A scyphistoma just 1 day after settlement.

jellyfish-dev-8.jpg

Here are 4 little polyps attached to a microbubble! This is a scyphistoma 5 days post-settlement.

jellyfish-dev-6b.jpg

Hydra-like mature scyphistoma undergoing asexual repdroduction (budding and stolon transfer).

jellyfish-dev-10b.jpg

The free swimming ephyrae, one step away from the medusa we all recognize as a jellyfish!

jelly-dev-medusa.jpg

The full citation for this work:

Craggs, J. & Robson, J. (2012). Observations of the life cycle of the scyphozoan jellyfish Aurelia aurita at the Horniman Museum Aquarium. Quekett Journal of Microscopy, 41, 615-621.

Tags: - -

Related Posts Widget for Blogs by LinkWithin

Leave a note

HI! I love thoughtful, intelligent, amusing comments! So thanks in advance for yours! Comments are manually approved before appearing above, thank you for your patience!







Advertise here through FM LIVING - Copyright NOTCOT INC 2005-2014 - Privacy Policy