An animal big enough to sit in

January 2nd, 2019

The story behind the biggest Neptune's cup in the collection of Naturalis Biodiversity Center

That’s right - this is a story about an animal big enough to sit in. It might be hard to comprehend when you look at it, but the Neptune’s cup (Cliona patera(Hardwicke, 1822)) is a sponge, and therefore an animal. Quite a basic animal - sponges have no nervous, digestive or circulatory systems, but they are multicellular organisms whose cells have a nucleus enclosed within membranes, which makes them animals nonetheless. Naturalis Biodiversity Center holds a few of these cup-shaped giants in the scientific collection, and they are all equally impressive. However, one of them stands out from the rest: a massive specimen, measuring more than a metre in diameter; its stalk sitting in an antique custom made underframe. What is the story behind this spectacular sponge and how did it end up in the Naturalis collection?

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Neptune’s cups in the Naturalis dry sponge collection (photo Karen van Dorp)

Naturalis dry sponge collection

Neptune’s cups occur in the western part of the South China and Eastern Archipelagic Seas. These places are far away from The Netherlands, and we can be quite certain that Jan den Doop (1889-1954) had never heard of Neptune’s cups when he set sail to the East. Jan had been an enthusiastic biology teacher; loved by his students but despised by his superiors for his unconventional way of teaching - he frequently organised biology trips off the beaten path for his pupils, and was known to deviate from regular teaching methods. Despite of the profound love for his profession, Jan grew tired of the friction his methods were causing with his superiors and decided to say farewell to the educational services in 1916. Coincidentally, the opportunity of a lifetime arose in that same year: a vacancy opened at the Deli testing station on the east coast of Sumatra, where the Dutch were cultivating tobacco. The caterpillar of a certain butterfly species was doing much damage to the plants, and the director of the testing station had released egg parasites on the plantations. He needed someone to investigate if these parasitic wasps had dispersed sufficiently over the fields. Jan applied successfully for the position and started his journey to the Dutch East Indies soon after.

As hard a worker as the planters on the fields; Jan was a master in maintaining a good work spirit in his new workplace. He combined hard working with lavish celebrations, and quickly became popular amongst his colleagues. He had lost one of his eyes due to an accident, and surprised attendees by tapping on his glass eye with a silver pencil whenever he wanted to propose a toast, instead of using a glass cup.

Jan spent all of his free Sundays and holidays roaming the surroundings of Medan and the adjoining regions Serdang and Langkat, and soon enough he became a real expert on the flora and fauna of Sumatra’s east coast. On more than one occasion Jan had to return to Medan earlier than he wished, due to the lack of financial resources. Nevertheless, these excursions produced a massive yield of observations and collected material.

One day in 1919, on one of his many trips to the mangrove forests on the coast, Jan encountered fishermen from Atjeh, who were bringing an enormous sponge to shore in the village of Rantau Padjang, a fishermen’s village on the coast of the regency of Serdang, Sumatra. He managed to acquire this truly unique specimen of a Neptune’s cup. It would not have been hard to imagine why this intriguing, goblet-shaped animal from the sea, which has a brilliant orange-yellow colour when fresh, had been given its common name. The Neptune’s cup had been described by major general Thomas Hardwicke in 1822(1), after which Hermann Schlegel renamed it as Poterion neptuni in 1858(2), and the genus was thoroughly revised by Pieter Harting in 1870(3).

Original description from the Neptune’s cup as Spongia patera, by major general Thomas Hardwicke in 1822.

Spongia patera

Harting described a large number of impressive specimens in his revision, but the Neptune’s cup collected by Jan den Doop exceeded all others in size. Jhr. Dr. Ir. Frans Cornelis van Heurn, a chemical engineer who got acquainted with Jan at the testing station in Medan and later worked on Java, got word of Jan’s find. Van Heurn took the specimen from Sumatra to Java, and made sure a baseframe was produced from local wood, to prevent damage to the stalk. Van Heurn was so impressed by the Neptune’s cup, that he made sure to have his wife Pietje and daughter photographed with it on Java. His daughter was actually sitting in the sponge when the photograph was taken.

Wife and daughter of F.C. van Heurn, photographed with the Neptune’s cup collected by Jan den Doop. From: Jan den Doop (1889-1954), een vooraanstaand bioloog. Bussum, Van den Hert 1955.

Poterion met vrouw en dochter Van Heurn

Van Heurn decided to ship the specimen to The Netherlands, convinced that the National Museum of Natural History in Leiden would be interested in incorporating such a specimen in their collections. A giant crate was produced, ‘so big six men would have fitted’, and the Neptune’s cup was shipped from Batavia to Leiden. There, Van Heurn offered the specimen to Eduard Daniël van Oort; director of the museum at the time, asking for compensation of the transport costs he had paid himself. Van Oort informed him that he couldn’t justify such a large sum, but was eager to purchase the specimen. Therefore, he managed to spread the sum over other museum expenses, and made sure the specimen was added to the Leiden collection in 1927(4&5).

Van Heurn published a biography of Jan den Doop in 1955, in which the photograph of the Neptune’s cup, and his wife and daughter was published. In this biography, Van Heurn also states that this specimen might well be the largest known Neptune’s cup known from natural history collections worldwide. Whether or not that is correct; this specimen should be considered as a unique and important exemplar within the relatively small collection of Neptune’s cups in natural history collections. After their discovery by the Western world, Neptune’s cups quickly became valuable collector’s items and were severely overharvested to the point of supposed extinction. According to historical records, the species was common during the last decades of the 18th century, but had basically vanished from all accessible waters by the early 1900s. Fortunately, in March 2011, a young specimen of the long-lost Neptune’s cup was discovered off Singapore’s southern islands during a routine survey dive by marine biologists. The encounter raises hope for a revival of the species in the places where it had been gone due to collecting and pollution. It is unlikely that a massive specimen like the one Jan den Doop collected will be ever deposited in a natural history collection again. Therefore - apart from its beautiful appearance - it is considered one of the most important natural history objects in the Naturalis Biodiversity Center sponge collection; with significant scientific, cultural and historic value.

The Neptune’s cup collected by Jan den Doop in its original wooden baseframe, deposited in the Naturalis collection under RMNH.POR.179 (photo Esther Dondorp). The stalk, which has broken off, is kept in a separate box.


Discover this Neptune's cup and other collection highlights on!

Written by Karen van Dorp,

Senior collection manager, Naturalis Biodiversity Center


1 Asiatic researches, or, Transactions of the Society instituted in Bengal for inquiring into the history and antiquities, the arts, sciences and literature of Asia. The Asiatic society of Bengal, Londen. Volume XIV, p.180 (a former reference in the biography of Jan den Doop by F.C. van Heurn is incorrect)

2 Handleiding tot de beoefening der dierkunde, II. Breda, boekdrukkerij van de Gebroeders Nys, voor rekening van de Koninklijke Akademie voor Zee- en Landmagt, 1857-1858, p549

3 Harting, P. (1870). Mémoire sur le genre Poterion. Société des Arts et des Sciences d'Utrecht, Pays Bas. 1870: 1-40, 11 pls

4 Annual report of the Rijksmuseum van Natuurlijke Historie, Leiden, 1927

5 Letter from F.C. Van Heurn to G.F. Mees, 3 March 1967 (archive Naturalis Biodiversity Center)