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2022-10-01 01:11 |
Logo Haus des Meers - Aqua Terra Zoo


Haus des Meeres researches the language of seahorses

After successfully breeding seahorses for many years, we are particularly happy to participate in an international research. Recently, together with Prof. Tacyana Ribeiro from the University of Paraiba in Brazil and the "fish whisperer" Prof. Friedrich Ladich from the Department of Behavioral Biology at the University of Vienna, we have carried out a valuable basic research about seahorses’ language. It was published in the renowned Journal of Zoology - PDF Download.

Numerous fishes speak - either to communicate something between each other or to frighten their enemies.
However we were surprised when we observed our seahorses for the first time (the slender seahorse - Hippocampus reidi), because they are not taciturn at all. We recorded two different sounds – a “click” sound and a “thunder” sound.

The click sound can be heard while eating or it's used as mating call. This sound is created by rubbing two bones, which are placed in a special joint at the back of the seahorse's head.
The tone is similar to tongue snapping.
We were able to record the second type of sound with technical finesse - with very sensitive underwater microphones (hydrophones). It was a low-frequency grumble which is produced when the seahorses are in need - for example when they are held either by a predator, or by the explorer's hand.

We can only speculate about the meaning of these sounds at the moment: The clicks may be a notification for the other seahorses that some food was found. Seahorses are very social animals, which also spend a lot of time to welcome each other twice a day.
However why they produce this click sound also as mating call, that remains a mystery.

The sounds are displayed in the two sonograms. The first one shows the click, the second sonogram displays the quieter but longer lasting rumbling sound.
Who really wants to hear seahorses, has to come in the Haus des Meeres. By the four meters long seahorses' aquarium, there is a loudspeaker installed, so that the visitors can listen to them.


Research in the Haus des Meeres

Marine Research in the concrete tower: On the 6th floor of the Flaktower, away from the visitor stream, there was a built a research station for all the scientific work. 

Jellyfish invasion in the Mediterranean: Researchers from the Haus des Meeres were able to prove that the jellyfish newcomer Phyllorhiza punctata is already reproducing in the Mediterranean. PDF


"Jellyfish polyps" - the ground-living jellyfish, produce hundreds of microscopic jellyfish at the end of their lives within a few weeks.


"Success model" - the floating bell (Phyllorhiza punctata), native to tropical Indo-Pacific: all marine areas colonized in last few decades are marked green. The originally colonized area is marked orange. 


For every seahorse mouth the right food – also a valuable seahorse-diet-research is carried out in the Haus des Meeres.


Phytoplankton is the basis of the artificial food chain in the Haus des Meeres. Varisous plankton species are grown in size-of-a-man cylinders.


A copepod just before laying eggs.


Valuable plankton: the Nauplius stage of crustacean, a coveted treat for seahorse babies.


The House des Meeres also supports the research of the oceans by providing marine resources and algae for scientific purposes. For example, flatworms were studied with an electron microscopic at the University of Vienna.

All currently available organisms are listed here.

Besides that, the Haus des Meeres is also planning to cooperate with SeaLife Pharma GmbH, which looks for pharmacologically active substances in the sea.


Bamboo sharks from the Haus des Meeres become "students" of the University of Bonn

Press release Dr. Vera Schlüssel

At the beginning of 2013, the Haus des Meeres kindly offered its department (Prof. Bleckmann, Comparative Neurophysiology, University of Bonn) twelve gray bamboo shark babies (Chiloscyllium griseum) for behavioral experiments. The aim of the work in Bonn is to find out whether sharks, as well as other vertebrates, have a local memory and can learn different orientation strategies and problem-specific strategies. Since April 2010, the young bamboo sharks have been trained in various spatial tasks together with some representatives of the Chiloscyllium punctatum (brown-banded bamboo shark) and Atelomycterus marmoratus (coral catshark) Since then they have learned a lot - they worked hard for their food and therefore definitely deserved it! Every day the sharks had to swim in a 2,5 m x 2,5 m, cross-shaped basin to predetermined places to get their food. Some sharks were trained to always orient themselves in a particular direction (always swim right or left), others had to swim to certain landmarks and others had to remember a particular place in the room. Orientation aids were a series of colorful, geometric patterns, attached to white walls around the basin. Every shark had ten passes per day and when everything ran smoothly, also ten pieces of fish for each fin-carrying student, as a reward. However there are many differences between personality and activity (similar to real students). There are lazy and industrious ones, courageous, anxious, deliberate, and hasty candidates. All in all, they are quite motivated and eager in the matter and at least at the time it looks as all of the sharks achieved the aim - only the last attempts are still pending. We have already carried out similar experiments on freshwater stingrays (Potamotrygon spec.) in 2004. There were found the same kinds of individual differences as by the sharks - fish is not just fish, as some of us might expect. However comparing sharks and stingrays, the first prize would go to the flatter family members: the baby stingrays were a lot cleverer than their relatives and also unbeatable in their enthusiasm. Let's see if the sharks beat them in the final round.

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