''Gnathia pilosus'' is the eighth gnathiid species to be described from

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

. It occurs on the warmer east coast compared to the other seven gnathiids found on the colder west and south coasts of South Africa. Gnathiids have a polymorphic and biphasic

life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring *Life-cycle hypothesis, ...

(reproductive stage and

ectoparasite 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 ...

larval stage). There are three larval stages with each stage having two forms, namely praniza and zuphea. The praniza is usually a replete, haematophagous phase while the zuphea is an unfed benthic dweller phase. Adults can be found in groups with a single male and up to 43 females and immature specimens. The free-living adults do not feed and are usually hidden in a cavity or

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

where

reproduction Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. Reproduction is a fundamental feature of all known life; each individual or ...

will occur. The larvae of gnathiid isopods are known to parasitise a large variety of

intertidal fish Coastal fish, also called inshore fish or neritic fish, inhabit the sea between the shoreline and the edge of the continental shelf. Since the continental shelf is usually less than deep, it follows that pelagic coastal fish are generally epi ...

worldwide. The taxonomic classification of gnathiids is usually based on the morphological characteristics of the adult male. The detailed descriptions of the female and larva, however, are also important for identifying these life stages to species level when collected in the absence of males.

Life cycle

''Gnathia pilosus'' is capable of breeding throughout the year, but with the majority breeding in summer and releasing their young in autumn. ''Gnathia pilosus'' larvae show decrease in growth over colder months. A decrease in water

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

may be the cause of slower

moulting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

in the winter months. The zuphea 1 is released from the female marsupium in the autumn months and subsequently attaches to their host fish. During feeding, the zuphea 1 transform into the praniza 1. The praniza 1 detaches from the host and rests on the bottom substrate, using the

blood meal Blood meal is a dry, inert powder made from blood, used as a high-nitrogen organic fertilizer and a high protein animal feed. N = 13.25%, P = 1.0%, K = 0.6%. It is one of the highest non-synthetic sources of nitrogen. It usually comes from cattle ...

to sustain itself until moulting into the zuphea 2 after 35 days. The zuphea 2 feeds on a host to become the praniza 2 and moults into a zuphea 3 which will also feed to become the very swollen praniza 3. Within a few weeks, the sex of the praniza 3 can be determined by the presence of either the

testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoster ...

in the male larva or thin

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...

strands in the female larvae. The male praniza 3 moults before the female praniza 3 in order to be ready for reproduction as soon as the females mature. This is important as the female requires fertilisation immediately after completing its moult. The larvae increase in length and width with each moult. Embryos develop in the female marsupium until released from the oostegite openings as zuphea 1 larvae. The life cycle from zuphea 1 to adult female fertilization ranges between 125 and 140 days.

References

External links

{{Taxonbar, from=Q2491838 Cymothoida Ectoparasites Animal parasites of fish Parasitic crustaceans Crustaceans described in 2008 Crustaceans of South Africa