#copepoda

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Did you know that Attheyella Yemanjae is a species of copepod only known to be found in Campo Úmido de la Onça in Brazil? This aquatic crustacean is named after Yemanjá, a Candomblé sea goddess and a Yoruba water spirit.

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Diaptomus spp.

A genus of freshwater copepods with a single eye spot, found in the Northern Hemisphere.

Copepod

(Sources - 1, 2, 3, 4)

Copepoda is a class of small crustaceans found in nearly every freshwater and saltwater biome, including the arctic. Some are planktonic, some live in sediment (benthic), some live underground in sinkholes or caves, some are parasitic, and some even live in wet terrestrial places such as bogs and the water-filled cups of bromeliads. They are small, usually 1 to 2 mm long, with a teardrop-shaped body and two pairs of antennae. Some polar copepods can reach up to 1 cm long. Most copepods have a single compound eye, usually bright red and in the centre of their transparent head. Subterranean species may be eyeless, and a couple genera have two eyes. Free-living copepods have a head fused with the first one or two thoracic segments, with the remainder of the thorax being comprised of three to five limbed segments. The first pair of appendages are maxillipeds, limbs used for feeding. The second pair beat like oars, aiding in swimming. They have a narrow abdomen with five leg-less segments, with tail-like rami at the tip. Meanwhile, the anatomy of parasitic copepods are so widely diverse that I simply do not have space to talk about it here. Copepods have incredibly fast reflexes, due to well-developed myelin sheaths, allowing them to escape predators at high speeds, often porpoising out of the water. Like ostracods, many species also use bioluminescence as a defense mechanism, using it to distract predators (see gif below).

When they are ready to mate, some copepod females leave a trail of pheromones for males to follow. When mating, the male will grip the female with his antennae and produce an adhesive spermatophore, then transfer it to the female’s genital opening. After fertilization, the eggs will sometimes be laid directly into the water column, or, in some species, the female will carry them in a sac until they hatch. In some pond-dwelling species, the eggs can remain dormant in the case of the pond drying up, waiting to hatch until more favorable conditions are present. The larvae hatch with a head and a tail but no true thorax or abdomen. In fact, the larvae look so different from their adult forms that many of them were once thought to be different species! They will moult 5-6 times before becoming a copepodid larva which resembles the adult, sans some limbs and segments. After 5 more moults they will reach adulthood.

The oldest known fossils of copepods are from the Late Carboniferous, but due to their small size and fragility, they are rare in the fossil record. However, these fossilized copepods seemed to belong to an extant (still living) family, meaning that copepods may have already reached the forms they are in now by the Carboniferous.

Propaganda under the cut:

Copepoda. This class is made up of copepods, microscopic aquatic zooplankton, though some live in sediments or are parasites.

Branchiopoda. This class is made up of fairy shrimp, clam shrimp, water fleas, and the shield shrimp. All members have gills on their appendages, including the mouthparts.

Copepod

Copepod