|Collecting Jellyfish Specimens – Images and Material|
Not all images of jellyfish are useful and not all images can be used to identify the species captured on camera, so it is worth remembering a few things before taking any pictures.
Specimens: Because there are few characters that can be used to separate similar looking species of jellyfish we need material of two different types, ideally from the same specimen. We would like material for genetic analysis and we would like material for morphological examination. If you cannot provide both sorts of material, then we would prefer to have the latter type: i.e. the whole specimen for morphological examination. Below you will find information on how you can fix and preserve the material we require, BUT there are a number of points to remember at the outset.
Genetic Material: In order to look at the DNA of a species, we need a small piece (thumb-nail size) of fresh, uncontaminated tissue. This tissue should be cut from the end of an oral arm (NOT Tentacle) and needs to be rinsed a couple of times quite vigorously in clean water (fresh or salt, doesn’t matter) to dislodge foreign matter. Then it needs to be placed into a small jar/tube with excess ethanol: by excess we mean about 10x as much ethanol as tissue. The ethanol MUST be 96% ethanol (by volume) (witblitz is no good as it is only about 40% ethanol), which can be obtained from most good local pharmacies. Don’t forget the label! The tissue specimen then needs to go into the fridge or freezer (it shouldn’t contaminate any foodstuffs, if properly secured) and then the ethanol needs to be replaced twice within the next 24 h. Once you have the specimen, let us know and we will arrange to both collect it and to reimburse you for the material costs involved (so remember to keep your receipt for the ethanol!).
Morphological Material: In order to collect specimens for morphological examination you will need a large bucket with a tightly fitting lid and some formalin. Formalin is an aqueous solution of formaldehyde (also known as methanal NOT methanol) and is a chemical that is used to fix and preserve biological specimens. It can be obtained from most good local pharmacies but when you get it please remember to ask whether you are getting formalin or formaldehyde – the difference is important as formalin is only 40% formaldehyde – though most pharmacies will likely stock formalin. Both chemicals are poisonous carcinogens, and when handling it you need to either wear gloves or put our hands into plastic bags: remember too to wash your hands afterwards. It must also be used in a well ventilated space – outdoors and away from the house is best. Formalin kills pretty much anything so be careful not to spill it on the lawn or in the fish-pond.
Once you have got your jellyfish specimen in a bucket, make sure that there is just enough seawater to cover it completely. Add the label: if you have also collected some genetic material make sure that the labels are the same on both material types and indicate (on both labels) that there is a corresponding “other” sample. This is important as it will help us link the genetics with the morphology. If you have collected more than one specimen of jellyfish and you are trying to put all into one bucket, you can thread the label through the centre of each jellyfish bell using a needle and thread (or equivalent). Okay, with the jellyfish in seawater, it is now time to add the formalin or formaldehyde. You need to add just enough to fix and preserve the sample without going overboard. The final concentration should be in the region of 5% formalin (by volume) [2% formaldehyde], so if your specimen/s plus seawater half-fills a 20 l bucket (equivalent to 10 l), then you need to add about 600 ml of formalin, or 250 ml of formaldehyde (it is better to add more than less). Put the lid on the bucket so that it fits tightly; swirl a couple of times to mix; rinse the bucket off with water and store in a dark, well ventilated space – ideally outside and away from the house or garage. Once you have the specimen, let us know and we will arrange to both collect it and to reimburse you for the material costs involved (so remember to keep your receipts for buckets and formalin).