Good news for your entire marine aquarium community: your shipment of live pods has arrived! After carefully opening your package and glancing over its contents, you immediately notice a small amount of detritus at the bottom of the bag. Have all of the pods died in transit, you wonder?
Rest assured that they are likely doing quite fine. The majority of what you see in the bag is an accumulation of dead phytoplankton and harmless, perfectly natural fecal pellets—copepod poop. There are probably thousands upon thousands of live copepods there. And all healthy, living animals poop. Moreover, a certain amount of particulate organic matter (POM) will almost certainly be present in the shipping water. This is simply because some POM will be present in high-end products such as Tisbee Pods, Apocalypse Pods, Tig Pods and 5280 Pods that include tiny juveniles, particularly if shipped in high densities. This makes for a very advantageous trade-off, as the inclusion of juveniles will make these products be of far greater immediate use to a greater number of your aquarium inhabitants as well as accelerate the establishment of permanent pod populations.
In actual fact, copepods generally ship quite well. They are extremely hardy and resilient creatures that are capable of tolerating extremely crowded and/or polluted conditions. Of course, given their relatively short lifespans and the huge numbers of individuals sent in a typical shipment, a few pods are certain to die while in transit. However, due to the presence of egg-bearing females, just as many individuals will be added to the population in this time.
Better suppliers will use cold/ heat packs in the package, as it is important to maintain a water temperature 45-95°F (8-35°C)—the tolerable water temperature range for copepods. AlgaeBarn copepods are cultured within the range of typical reef aquarium temperatures. Cold packs protect the pods from overheating, as they experience thermal stress at water temperatures that exceed 95°F (35°C). Keeping the Pods cool serves to slow their metabolism, but it is not a necessity. A reduced metabolism has two benefits; it slows the consumption of oxygen as well as reducing the excretion of waste products. Contrary to some assertions, the use of cold packs is not intended to maintain a temperature of 55°F.
It is true that in cases where packages are damaged, exposed to extreme weather or not delivered on time, DOAs can occur. In such cases, it is important to know what to look for before taking further action. As even adult copepods of some species can be difficult to see with the naked human eye, one must look very closely to assess their condition. Backlighting with a powerful flashlight can help with this. Better yet is observation under a microscope, if one is available. The most obvious indication of health is vigorous physical activity. A good indication of health and vitality is their characteristically jerky movement through the water column. Benthic forms may be observed skirting over the inner surface of the shipping bag.
Because the presence of detritus in the bag is a common concern, one should know what type and amount of detritus is normal and acceptable. In a typical, properly shipped bag of healthy copepods, any settled POM should look like a small patch of detritus at the bottom of the bag. The way to tell if this is just natural waste is to look for movement in water column. In a healthy bag of copepods, you should be able to see thousands of actively swimming copepods that look like moving dust specs in the water column. Here is a photo of normal detritus accumulation: