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Finding Maude Delap

In one of the most south-westerly points of Ireland, the boarded windows of a derelict house resist the powerful storms that carve the coastline of Valentia Island. Its cracked and crumbling exterior give no indication that it was once home to a pioneering self-taught marine biologist who made ground-breaking scientific breakthroughs in this remote corner of Ireland. Maude Jane Delap moved to Valentia Island from Donegal with her family in 1874. Unlike their brothers, Maude and her sisters were home-schooled. Nevertheless, she devoted her life to studying and observing her natural environment and the species which inhabited it. Her biggest passion was marine biology, a science to which she made internationally important contributions despite being self-taught and only having a rudimentary laboratory in her house.

Delap collaborated with marine biologists working at Plymouth Marine Biological Station and University College London. She carried out extensive records of the plankton communities of Valentia Harbour between 1895 and 1923. This work on plankton is still cited today as it gives insight into the plankton communities of Irish waters. Maude Delap’s biggest contribution to science was her culture and rearing of jellyfish. She was the first person in the world to have reared jellyfish within an aquarium and to publish her observations of the full reproductive cycle. Her work is still valuable and inspirational to today’s scientists and was so respected by the scientific community at the time, that Delap was offered a fellowship by Plymouth Marine Biological Station in 1906. This was a significant honour. However, her father reportedly forced her to refuse the offer, stating “No daughter of mine will leave home except as a married woman.” Maude stayed on Valentia, continuing to carry out her research, until her death in 1953. Maude Delap was a true Irish naturalist, and her legacy deserves to be celebrated. 

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Project Summary
By Jane Sheehan, LIVE Knowledge Gatherer

Maude Delap is remembered locally, and her work is well known among the scientific community, however there are gaps in knowledge about how she worked and carried out some of her research. There is also an urgent need to catalogue and adequately archive her notebooks, letters, and other documents. As part of my role as a Knowledge Gather for LIVE, I plan to gather this research, along with the existing and available research, and bring it to the public and local communities. I hope to summarize her scientific findings and make them understandable and accessible for people. Additionally, I hope to carry out my own research on Iveragh’s jellyfish and plankton communities. Jellyfish and other plankton are not the most charismatic of our marine creatures, but they are a critical and fascinating ingredient in healthy oceans. By studying them, we can learn more about the health of our oceans and additionally, we can truly appreciate the work that Maude Delap carried out.

Read Jane's blog - My personal quest to find Maude Delap below.

Maude Delap’s 5 main contributions to science


Maude Delap was the first person in the world to document and publish the full process of rearing jellyfish in an aquarium. Culturing jellyfish is a very difficult task however, Maude raised 4 species of jellyfish native to Irish waters.


Maude Delap continuously monitored plankton communities of Valentia Harbour from 1899-1923. Because of this work, we are able to view plankton community structure and abundance from a hundred years ago. These are some of our earliest records of plankton in Irish waters.


She is one of the first people to observe the very complex life cycle of a jellyfish. At the time, the different stages of the life cycle were often mistaken for a whole new species of jellyfish! Maude’s experiments and ability to observe the jellyfish life cycle meant that she was able to determine which stage corresponded to which jellyfish.


Discovered a species of sea anemone in the eelgrass of Valentia Harbour that has not been found anywhere else since. The Burrowing Sea Anemone was named “Edwardsia delapiae” by Thomas Alan Stephenson in his book British Sea Anemones. He noted that "Miss Delap's skill and persistence in collecting rare species are indefatigable.".


Maude Delap was the first person to focus on the importance of understanding the jellyfish diet in captive rearing. She determined the diet of the jellyfish by a process of trial and error.

Walk in the shoes of
Maude Delap

Interested in walking in the steps of Maude Delap? Check out our interactive guide, which shows some of the important points of interest on Valentia Island which overlap with Maude’s history.

Delap sisters Courtesy of the National Science & Engineering Plaques Committee.jpeg


Maude Delap published several journal articles and short notes throughout her lifetime. The following is comprehensive list of her work.

A. Plankton studies

M. J. Delap and C. Delap. 1905. Notes on the plankton of Valentia Harbour, 1899-1901. Annual report of Fisheries, Ireland 1902-03. II ((i)) 3-19.

M. J. Delap and C. Delap. 1906. Notes on the plankton of Valentia Harbour, 1902-05. Fisheries Ireland, Scientific Investigations 1905. III (VII (i)) 141-159

M. J. Delap. 1924. Further notes on the plankton of Valentia Harbour 1906-1923. Irish Naturalists' Journal. 33 (1) 1-6

B. Culturing jellyfish

M. J. Delap. 1901. Notes on the rearing of Chrysaora isosceles in an aquarium. Irish Naturalist. 10 (2) 25-28.

M. J. Delap. 1905. Notes on the rearing, in an aquarium of Cyanea Lamarcki, Peron et Lesueur. Annual report of Fisheries, Ireland 1902-03. II (I(ii)) 20-22.

M. J. Delap. 1906. Notes on the rearing, in an aquarium, of Aurelia aurita, L. and Pelagia perla (Slabber). Fisheries Ireland, Scientific Investigations

C. Short notes

M. J. Delap. 1904. Seal caught on a handline. Irish Naturalist. 13 (2) 49.

1905. VII 160-164. M. J. Delap. 1921. Drift on the Kerry coast. Irish Naturalist. 30 (3) 40.

D. Diary recordings

M. J. Delap. 1899-1904. Diary recording observations on Coelenterata and other marine animals around Valencia, Ireland.


Archives on Maude Delap can be found at the following:

The Valentia Heritage Centre has photographs of the Delap family, a sketchbook belonging to Maude and her famous golden microscope and case.

The National History Museum, Dublin houses letters of correspondence from Maude and her family to the Keeper of the museum. Additionally, the specimens the Delap family sent to the museum are still present within their archives.


Within the National History Museum, London there are letters of correspondence between Maude Delap and Edward T. Browne, along with some sketches she sent to him.

Jellyfish and Plankton Resources

To learn more about jellyfish and plankton of Irish and Welsh waters, check out the following resources.​

Submit your sighting

Have you come across a sighting of a jellyfish on your travels? Please submit your sightings to The Big Jellyfish Hunt and the National Biodiversity Data Centre.

Plankton Resources
Jellyfish Gallery
Coming Soon: Through the Looking Glass

Have you ever wondered what plankton looks like? Here we will catalogue some of the common species of plankton. Some of these species are the very ones Maude Delap would have seen through her microscope!

Daily updates

If you would like to see daily updates on Maude Delap, follow the hashtag #FindingMaudeDelap on twitter, where our Knowledge Gatherer Jane posts new information she uncovers on Maude’s life.

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