''Pennella'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of large

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

s which are common

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s of large

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

fishes. They begin their life cycle as a series of free-swimming

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

. The females metamorphose into a parasitic stage when they attach to a host and enter into its skin. The males are free swimming. Due to their large size and mesoparasitic life history there have been a number of studies of ''Pennella'', the members of which are among the largest of the parasitic Copepoda. All species are found as adults buried into the flesh of marine bony fish, except for a single species, ''Pennella balaenopterae'' which can be found in the muscles and blubber of

cetacean Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...

s and occasionally other

marine mammal Marine mammals are aquatic mammals that rely on the ocean and other marine ecosystems for their existence. They include animals such as seals, whales, manatees, sea otters and polar bears. They are an informal group, unified only by their reli ...

s, and is the largest species of copepod.

Biology

Like most parasitic copepods it is the female which is parasitic in ''Pennella'' while the males are free swimming. The female has a two host life cycle and egg production commences when an inseminated female settles on its ultimate host, usually a large marine fish such as a member of the cod family

Gadidae The Gadidae are a family of marine fish, included in the order Gadiformes, known as the cods, codfishes, or true cods. It contains several commercially important fishes, including the cod, haddock, whiting, and pollock. Most gadid species are ...

tuna A tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length: ...

. The intermediate host is usually a

flatfish A flatfish is a member of the Ray-finned fish, ray-finned demersal fish order (biology), order Pleuronectiformes, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the ...

or a

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

. Before the parasite settles on the intermediate host there are two free swimming or copepodid larval stages, after which it settles on the gill tips of the intermediate host as a

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

chalimus larva. After four chalimus stages on the intermediate host the parasite becomes sexually mature and the free swimming males begin to copulate with the females while they are still sessile, a week after attaining maturity the females leave the intermediate host. Whether or not the females have copulated they become free swimming and the males will inseminate free swimming females as well. After a brief period as a free swimming animal the female infects its ultimate host and begins its main period of adult growth and begins to release eggs into the water.

Species

The genus contains 15 species: *''

Pennella balaenopterae ''Pennella balaenopterae'' is a large ectoparasitic copepod specialising in parasitising marine mammals. It is the largest member of the genus ''Pennella'', the other species of which are parasites of larger marine fish. Description ''P. ba ...

'' Koren & Danielssen, 1877 *''

Pennella cylindrica ''Pennella'' is a genus of large copepods which are common parasites of large pelagic fishes. They begin their life cycle as a series of free-swimming planktonic larvae. The females metamorphose into a parasitic stage when they attach to a host a ...

'' (Brady, 1883) *''

Pennella diodontis ''Pennella'' is a genus of large copepods which are common parasites of large pelagic fishes. They begin their life cycle as a series of free-swimming planktonic larvae. The females metamorphose into a parasitic stage when they attach to a host a ...

'' Oken, 1815 *''

Pennella elegans ''Pennella'' is a genus of large copepods which are common parasites of large pelagic fishes. They begin their life cycle as a series of free-swimming planktonic larvae. The females metamorphose into a parasitic stage when they attach to a host a ...

'' Gnanamuthu, 1957 *''

Pennella elongata ''Pennella'' is a genus of large copepods which are common parasites of large pelagic fishes. They begin their life cycle as a series of free-swimming planktonic larvae. The females metamorphose into a parasitic stage when they attach to a host a ...

'' (Lubbock, 1860) *''

Pennella exocoeti ''Pennella exocoeti'' is a large ectoparasitic copepod, a specialist parasite of flying fish. The adult female copepod clings to the fish's gills or skin and feeds on its body fluids. Taxonomy ''Pennella exocoeti'' was first described by the Da ...

'' (Holten, 1802) *''

Pennella filosa ''Pennella'' is a genus of large copepods which are common parasites of large pelagic fishes. They begin their life cycle as a series of free-swimming planktonic larvae. The females metamorphose into a parasitic stage when they attach to a host a ...

'' (Linnaeus, 1758) *''

Pennella hawaiiensis ''Pennella'' is a genus of large copepods which are common parasites of large pelagic fishes. They begin their life cycle as a series of free-swimming planktonic larvae. The females metamorphose into a parasitic stage when they attach to a host a ...

'' Kazachenko & Kurochkin, 1974 *''

Pennella instructa ''Pennella'' is a genus of large copepods which are common parasites of large pelagic fishes. They begin their life cycle as a series of free-swimming planktonic larvae. The females metamorphose into a parasitic stage when they attach to a host a ...

'' C. B. Wilson, 1917 *''

Pennella makaira ''Pennella'' is a genus of large copepods which are common parasites of large pelagic fishes. They begin their life cycle as a series of free-swimming planktonic larvae. The females metamorphose into a parasitic stage when they attach to a host a ...

'' Hogans, 1988 *'' Pennella oxyporhamphi'' Sebastian, 1966 *'' Pennella sagitta'' (Linnaeus, 1758) *'' Pennella selaris'' Kirtisinghe, 1964 *'' Pennella tridentata'' Listowsky, 1892 *''

Pennella varians ''Pennella'' is a genus of large copepods which are common parasites of large pelagic fishes. They begin their life cycle as a series of free-swimming planktonic larvae. The females metamorphose into a parasitic stage when they attach to a host a ...

'' Steenstrup & Lütken, 1861

References

External links

{{Taxonbar, from=Q4291877 Siphonostomatoida