Clytia brevithecata

Invasion History

First Galapagos Record: 1992

---

General Invasion History:

The hydrozoan Clytia brevithecata was described from New Britain, Papua New Guinea was described by Thornley in 1900. A very similar hydrozoan, C. hummelincki, was described from Martinique in the West Indies by Leloup, in 1935. Genetic evidence indicates that the two forms are conspecific, and widely distributed in the Atlantic and Pacific (Calder and Faucci  2021; Calder et al. 2023; WoRMs Editorial Board 2023). Overall, it ranges form Bermuda to Brazil and the Mediterranean to South Africa, and the Hawaiian Islands to Papua New Guinea to the Hawaiian Islands (Gravili et al. 2008; Calder and Faucci 2021; Mendonça et al. 2022) although the records are spotty.  Gravili et al. (2008) considered C. brevithecata (as C. hummleincki) to be a recent introduction to the western Mediterranean, although hydroids of this size were poorly studied in the eastern Mediterranean. 

Clytia brevithecata (as C. hummelincki) was collected in the Galapagos Islands in 2000 (Calder et al. 2003), its first report from the Tropical Eastern Pacific. In 2018, two specimens were collected on Cocos Island, Costa Rica. This species now considered introduced in the Galapagos and Cocos Island by Calder et al. (2022).

 

Invasion History in the Galapagos:

Clytia brevithecata (as C. hummelincki) was collected in 1992 and again in 2000 on Isla San Cristobal, and on Isla Wolf in 2000 (Calder et al. 2003).  These were the first reports of this hydroid from the Eastern Pacific (Calder et al. 2003). Clytia brevithecata is now regarded as an introduction in the Eastern Tropical Pacific (Calder et al. 2022).

 

 

Invasion history elsewhere in the world:

Clytia brevithecata (including its synonym C. hummleincki) is widely distributed in the tropical and warm-temperate Atlantic and Pacific, from Bermuda to Brazil, the Mediterranean to South Africa, the northern Hawaiian Islands to Papua New Guinea (Gravili et al. 2008; Klemo and Attril 2019; Calder and Faucci 2020; Mendonça et al. 2022; Calder et al. 2022).  We consider much of this range to be native or cryptogenic. This hydroid is small (3–6 mm) and grows on shells, rocks, vegetation, and other hydroids and so is easily overlooked, which may contribute to the spotty records (Gravili et al. 2008; Klemo and Attril 2019). However, Gravili regarded it as a recent introduction (first record in 1991) in the Western Mediterranean, from Italy to Spain. There was limited sampling of hydroids in the Eastern Mediterranean. It is easily transported in hull fouling, and has a planktonic medusa, which can be transported in ballast water (Gravilli et al. 2008).

It is regarded as introduced in the Galapagos islands, where it was first collected in 1992 (Calder et al. 2003), and is considered introduced to Cocos Island as two specimens were collected there in 2018 (Calder et al. 2022). 

Description

The hydroids of Clytia brevithecata grow from stolons spreading over the ground, with unbranched stalks, marked by annulations (rings). The stalks are topped by cup-shaped hydrothecae, about 0.30mm x .35mm, with a crenulated (scalloped) edge containing a mouth surrounded ~20 threadlike tentacles. The feeding hydroids are about 3-6 mm tall. Pear-shaped reproductive polyps (gonothecae) also grow from the stolons, and produce medusa buds. The medusae are hemispherical and growing from 1 to 4 mm diameter in about 12 days, with tentacles increasing from 4 to 8mm.  The medusae are sexual and release eggs and sperm, which fuse to form planula larvae and settle to from new hydroid colonies (Gravili et al. 2008).

Clytia brevithecata grows in spreading colonies on stones, shells, vegetation, and man-made structures. Clytia brevithecata is now considered to have a wide native and cryptogenic range in the tropical to warm-temperate Atlantic and Pacific. In the Atlantic, it ranges from Bermuda to Brazil, and the Mediterranean to South Africa, and in the Pacific from the Hawaiian Islands to Papua New Guinea. It is considered to be a possible introduction in the Western Mediterranean  and the Tropical Pacific, where it has been recently found on the Galapagos Islands and on Cocos Island, Costa Rica.  This hydrozoan has the potential to be introduced in ballast water or fouling.

---

Taxonomy

Ecology

General:

Clytia brevithecata grows in spreading colonies on stones, shells, vegetation, and man-made structures. It is now considered to have a wide native and cryptogenic range in the tropical to warm-temperate Atlantic and Pacific. In the Atlantic, it ranges from Bermuda to Brazil, and the Mediterranean to South Africa, and in the Pacific from the Hawaiian Islands to Papua New Guinea. Its range suggests limited tolerance to cold temperatures and low salinity (Gravili et al, 2008; Kelmo and Attril, 2019; Calder and Faucci 2021). The hydroids and medusae both feed largely on zooplankton (Gravilli et al. 2008).

Food:

Zooplankton

Consumers:

Nudibranchs, other invertebrates

Competitors:

Ohrer hydroids; meduseae

Trophic Status:

Suspension feeder

---

Habitats

General Habitat	Bedrock	None
General Habitat	Marinas & Docks	None
Salinity Range	Euhaline	30-40 PSU
Vertical Habitat	Epibenthic	None

---

Life History

Hydroids of Clytia brevithecata reproduce asexually, as polyps growing from a pear-shaped reproductive polyps (gonothecae) also grow from the stolons, and produce medusa buds.  The medusae are hemispherical and growing from 1 to 4 mm diameter in at least 12 days, with tentacles increasing from 4 to 8mm. The medusae are sexual and release eggs and sperm that fuse to form planula larvae and settle to form new hydroid colonies. However, cultured medusae did not mature or produce eggs (Gravili et al. 2008).

---

Tolerances and Life History Parameters

Maximum Height (mm)

6

General Impacts

No impacts have been reported for Clytia brevithecata.

---

References

Mendonça, Luana M. Castro; Castro, Luana M.; ; Haddad, Maria A. ; (2022) Taxonomy and diversity of hydroids (Cnidaria: Hydrozoa) of Sergipe, Northeast Brazil, Zoologia 30: Published online

Calder, D. R.; Mallinson, J. J.; Collins, K.; Hickman, C. P. (2003) Additions to the hydroids (cnidaria) of the Galapagos, with a list of species reported from the islands, Journal of Natural History 37: 1173-1218

Calder, Dale R.; Carlton, James T.; Keith, Inti; Ashton, Gail V. ;Larson, Kristen; Ruiz, Gregory M.; Herrera, Esteban; Golfin, Geiner (2022) Biofouling hydroids (Cnidaria: Hydrozoa) from a tropical Eastern Pacific island, with remarks on their biogeography, Journal of Natural History 56(9-12): 565-606
https://doi.org/10.1080/00222933.2022.2068387

Calder, Dale; Faucci, Ansuschka (2021) Shallow water hydroids (Cnidaria, Hydrozoa) from the 2002 NOWRAMP cruise to the Northwestern Hawaiian Islands, Zootaxa 5085(1): 1-73
https://doi.org/10.11646/zootaxa.5085.1.1

Gravili, Cinzia; D’Ambrosio, Paolo; Di Camillo, Cristina; Renna, Giuseppina; Bouillon, Jean; Boero, Ferdinando (2008) Clytia hummelincki (Hydroidomedusae: Leptomedusae) in the Mediterranean Sea, Journal of the Marine Biological Association of the United Kingdom 88(8): 1547-1553

Kelmo, Francisco; Attrill, Martin J. (2003) Shallow water Campanulariidae (Hydrozoa, Leptothecatae) from northern Bahia, Brazil, Revista de Biologia Tropical 51(1): 123-146

WoRMS Editorial Board (2021). 2021 World Register of Marine Species. https://www.marinespecies.org/

---