Marine Creatures of the Northern Gulf of Mexico – Copepods

So far in this series we have been discussing microscopic creatures in the northern Gulf of Mexico that are single celled – though many may be linked together in chains.  In this article we will begin discussing microscopic creatures that are multicellular.

When you do a plankton tow in the northern Gulf, and have a look under the microscope, you will notice most of the moving/swimming plankton are these bug-looking creatures scientists call copepods.  The Latin origin of their name (oar-foot) comes from the motion of their swimming legs, which resembles rowing with an oar.  They twist and turn all within the field of view, moving quite fast.  You will not miss them.

It has been stated that the copepods produce some of the largest biomass in the oceans, there are TONS of them within the water column.  They swim all through the water column feeding on the phytoplankton we have already discussed in this series.  They play a very important role in the food chain connecting the photosynthetic phytoplankton – the “grasses of the sea” – with the consuming animals of the northern Gulf.  It has been stated that the copepods are most likely in every creature’s food chain – making them one of the most important members of the northern Gulf of Mexico community.  In addition to connecting the marine animals to the primary producers, they also are important at removing carbon from the surface waters of the oceans, reducing the negative impacts of excessive carbon in the atmosphere.

As mentioned, they are multicellular but still microscopic.  We also mentioned they look like bugs and are in the Phylum Arthropoda along with the true bugs.  Arthropods have jointed legs, antennae, and an exoskeleton that must be shed during growth – and this is the case with the copepods.  They are in the Subphylum Crustacea – indicating they are related to shrimps and crabs.  Most are between 1-2mm in length but can reach lengths of 10mm and large to be seen in a glass of sea water as flecks darting about.  Most have a single compound eye and, along with their antennae, can detect the movements of both predators and prey.

Many larger creatures of the northern Gulf feed on them directly – such as the plankton feeding fish and whales.  But most include them as a lower part of their food chain.  Copepods can sense the presence of such predators and are quite fast swimmers.  They have been clocked at 295 feet in one hour – which is equivalent to a human swimming at 50mph!

Though you will never see them when you visit the beaches, they are one of the most abundant, and ecologically important, creatures in the northern Gulf of Mexico.

 

References

 Copepods. National Museum of Natural History. https://naturalhistory.si.edu/research/invertebrate-zoology/research/copepods.

 Copepod. Monterey Bay Aquarium. https://www.montereybayaquarium.org/animals/animals-a-to-z/copepod.

 Walter, T.C.; Boxshall, G. (2024). World of Copepods Database. Accessed at https://www.marinespecies.org/copepoda on 2024-11-17. doi:10.14284/356.