The Southern eagle ray (''Myliobatis goodei''), sometimes known as the Southern eagle fish or the rockfish, is a
ray
Ray may refer to:
Fish
* Ray (fish), any cartilaginous fish of the superorder Batoidea
* Ray (fish fin anatomy), a bony or horny spine on a fin
Science and mathematics
* Ray (geometry), half of a line proceeding from an initial point
* Ray (gra ...
species in the family
Myliobatidae. It lives in waters just off of the Atlantic coast, from the tip of Florida down to Argentina, inhabiting estuaries or bays to give birth during spring and summer and migrating to the open sea in autumn and winter. It has an average width of 99 centimeters, and a length of 60 centimeters. It is often confused with the
bullnose ray
The bullnose ray (''Myliobatis freminvillii'') is an eagle ray, which is widely distributed in the western Atlantic. It is found at depth above in coastal waters from Cape Cod down to Argentina, but is absent from parts of the western central At ...
, a related species in the genus ''
Myliobatis
''Myliobatis'' is a genus of eagle rays in the family Myliobatidae.
Description
''Myliobatis'' species can reach a width up to about . Their bodies consist of a rhomboidal disc, wider than long, with one dorsal fin. The head is broad and short, ...
'', due to the two species' similarities in appearance.
Taxonomy
Samuel Garman
Samuel Walton Garman (June 5, 1843 – September 30, 1927), or "Garmann" as he sometimes styled himself, was a naturalist/zoologist from Pennsylvania. He became noted as an ichthyologist and herpetologist.
Biography
Garman was born in Indian ...
described the southern eagle ray in 1885.
Distribution and habitat
The Southern eagle ray lives on various parts of the Atlanta coast. Sightings have been reported from the coast of Southern
Mexico
Mexico ( Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guate ...
all the way down to
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, t ...
, as well as on the coast of
Florida
Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, a ...
. The specific countries that the Southern eagle ray is native to are Argentina,
Belize
Belize (; bzj, Bileez) is a Caribbean and Central American country on the northeastern coast of Central America. It is bordered by Mexico to the north, the Caribbean Sea to the east, and Guatemala to the west and south. It also shares a wa ...
,
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
,
Colombia,
Costa Rica,
French Guiana
French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas departments and regions of France, overseas department/region and single territorial collectivity of France on the northern Atlantic ...
,
Guyana,
Honduras, Mexico,
Nicaragua
Nicaragua (; ), officially the Republic of Nicaragua (), is the largest Sovereign state, country in Central America, bordered by Honduras to the north, the Caribbean Sea, Caribbean to the east, Costa Rica to the south, and the Pacific Ocean to ...
,
Panama
Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Co ...
,
Suriname
Suriname (; srn, Sranankondre or ), officially the Republic of Suriname ( nl, Republiek Suriname , srn, Ripolik fu Sranan), is a country on the northeastern Atlantic coast of South America. It is bordered by the Atlantic Ocean to the north ...
,
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...
,
Uruguay
Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...
, and
Venezuela
Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in ...
. A sighting was also reported in the island of
Maldives
The Maldives, officially the Republic of Maldives,, ) and historically known as the Maldive Islands, is a country and archipelagic state in South Asia in the Indian Ocean. The Maldives is southwest of Sri Lanka and India, about from the A ...
in August 2012, and then three more were reported in
Australia.
The Southern eagle ray lives in shallow waters, mostly under 100 meters, but it can live in depths of up to 200.
This is a significant contrast from the
bullnose ray
The bullnose ray (''Myliobatis freminvillii'') is an eagle ray, which is widely distributed in the western Atlantic. It is found at depth above in coastal waters from Cape Cod down to Argentina, but is absent from parts of the western central At ...
, which most commonly lives in depths of no more than 10 meters. It is
benthopelagic
The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer o ...
, feeding in and inhabiting the areas just above the ocean floor, typically in
brackish
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...
water. It prefers waters with a soft
seabed
The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'.
The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...
, composed of elements such as
mud
A MUD (; originally multi-user dungeon, with later variants multi-user dimension and multi-user domain) is a Multiplayer video game, multiplayer Time-keeping systems in games#Real-time, real-time virtual world, usually Text-based game, text-bas ...
,
sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a soil texture, textur ...
, or
sea grass
Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families ( Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the ...
.
Description
The Southern eagle ray's average length is , but some specimens have reached up to .
The species is somewhat wider than it is long, with its disc being an average of wide.
It does not have spines on its disc. The Southern eagle ray usually has a dark brown colored upper side, while most of its underside is a light shade of brown or white, with the outer edges often being darker.
Comparison with the bullnose ray
The Southern eagle ray's appearance is similar to that of the
bullnose ray
The bullnose ray (''Myliobatis freminvillii'') is an eagle ray, which is widely distributed in the western Atlantic. It is found at depth above in coastal waters from Cape Cod down to Argentina, but is absent from parts of the western central At ...
, causing the two to often be confused.
The following table shows the similarities and differences between the two related species:
Behavior
The Southern eagle ray is a carnivore, mostly feeding on small invertebrates, such as
shrimp
Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...
,
crabs
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting " tail" ( abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in al ...
, and
gastropods
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda ().
This class comprises snails and slugs from saltwater, from freshwater, and from land. ...
.
The Southern eagle ray migrates seasonally. Adults inhabit the open sea during the autumn and winter, and return to their home location, which is usually an
estuary
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...
or a
bay
A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a gulf, sea, sound, or bight. A cove is a small, circular bay with a nar ...
, in the spring and summer, to give birth. The young that are born in summer usually wait until the end of the next summer before they migrate into the open waters, while those who are born in spring do this after the first summer passes. They then return to their home location again in the spring and summer, to give birth themselves. Little else is known about the ecology and reproduction of the Southern eagle ray.
Reproduction
The Southern eagle ray exhibits
ovoviviparity
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...
, meaning that the eggs remain inside the mother's body until they are ready to hatch.
Embryos
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm c ...
feed on yolk when they are first developed. As they develop further, they start receiving nourishment by absorbing
uterine fluid from their mother instead.
Population, conservation, and status
The Southern eagle ray is a rather common species, much more abundant than the bullnose ray. The species is caught by fisheries, sometimes intentionally but often as a bycatch.
IUCN currently lists it as vulnerable. There are currently no conservation measures in place for this species.
The Southern eagle ray is often caught intentionally in fishing nets by artisanal fisheries. It is also quite often a bycatch component for trawl fisheries, especially in Caribbean South America and parts of Brazil. It is thought that this may eventually lead to its population declining in certain regions. It is also commonly caught in Venezuela, most often as a bycatch component. The number of reported catches of this species in Venezuela has increased greatly over the years, particularly throughout the 1980s and 1990s. The Southern eagle ray is also a common bycatch of various fisheries in southern Brazil, due to intensive fishing activities. Other batoids are commonly caught in this area as well. Although the intensive fishing has caused a significant decline in many batoid species, it is unknown how this affects eagle rays.
Parasites
The Southern eagle ray has several parasites that infect it.
* ''
Aberrapex arrhynchum''
* ''
Aberrapex ludmilae''
* ''
Aberrapex sanmartini''
* ''
Acanthobothrium
Onchobothriidae is a family of flatworms belonging to the order Onchoproteocephalidea
Onchoproteocephalidea is an order of flatworms belonging to the class Cestoda.
Families:
* Onchobothriidae
* Prosobothriidae
* Proteocephalidae
Proteo ...
sp.''
* ''
Caulobothrium ostrowskiae''
* ''
Caulobothrium uruguayensis''
* ''
Halysioncum megacanthum''
* ''
Mecistobothrium oblongum''
* ''
Parachristianella damiani''
* ''
Phyllobothrium myliobatidis''
References
{{Authority control
Myliobatis
Taxa named by Samuel Garman
Fish of the Western Atlantic
Fish of the Indian Ocean
Fish described in 1885