Classification

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Myliobatiformes
Family: Myliobatidae
Genus: Aetobatus
Species: Aetobus narinari

Domain: EukaryaClustered bonnet mushrooms are eukaryotic organisms. Photo credit: Wikimedia Commons.
    Eukarya is one of the three domains of life, and probably the one that you are most familiar with. Organisms classified in the domain Eukarya contain nuclei in their cells, along with other membrane bound organelles such as mitochondria and ribosomes. This domain contains species that have considerable variation, from plants and animals, to diatoms and radiolarians. If you want to learn about other eukaryotic organisms, check out these awesome pages about watermelons and ergot.

 

Figure 1. Phylogenetic tree depicting the relationships between the major clades in the eukaryotic domain. Spotted eagle rays are members of the Opisthokonta clade. This clade encompasses diverse organisms, including animals and fungi. Opisthokonts are most closely related to the Amoebozoans, which includes slime molds and lobose amoebae (Modified from Gerrish, 2014).

Mexican wolves are multicellular heterotrophs in the Kingdom Animalia. Photo credit: Wikimedia Commons.Kingdom: Animalia
    Organisms, including eagle spotted rays, are classified into the kingdom Animalia because of various unifying traits. Animals are multicellular heterotrophs that are unable to synthesize their own organic compounds, and need to obtain nutrients from the food they digest. Their cells contain no cell walls and all animals, except sponges, have true tissues, which is a group of cells performing similar functions. Some animals that are included in this kingdom include jellyfish, chordates, and arthropods. Interested in arthropods? Check out this cool dragonfly.                       

Phylum: ChordataMallard ducks are members of the Phylum Chordata. Photo credit: Wikimedia Commons.
    The major trait that unifies organisms in the phylum Chordata is the presence of a notochord, which is an integral component to embryonic development. Notochords organize the structures of a developing embryo and also offers skeletal support. Most chordates lose their notochord as they mature into adults, but in some groups such as fishes, the notochord develops into a flexible rod that gives support to the body while swimming. If you're interested in learning about another organism in this phylum, check out this western fence lizard.

 

Figure 2. Phylogenetic tree showing the relationships between the phylums found in the animal kingdom. Spotted eagles rays are classified in the phylum Chordata. They are most closely related to organisms found in the phylum Echinodermata. Organisms found in the Echinodermata and Chordata phylums are deuterostomes, triploblastic, and have bilateral symmetry, but there are also many differences. Echinoderms have spiny skin and a water vascular system, while Chordates have a notochord at some point during development (Modified from Gerrish, 2014).

White sharks belong in the Class Chondrichthyes. Photo credit: Wikimedia Commons.Class: Chondrichthyes
     The main characteristic of the organisms classified in the class Chondricthyes is a cartilegenous skeleton. Their notochord, which is a defining feature of Chordates, is replaced by cartilage as the organism ages. Teeth-like placoid scales cover their skin, making them feel like sandpaper. There are two subclasses: the Elasmobrachii, which includes sharks, rays, and skates; and the Holocephali, consisting of chimaeras.


Stingrays are included in the Order Myliobatiformes. Photo credit: Wikimedia Commons.
Order: Myliobatiformes
    The order Myliobatiformes consists of batoid fishes (rays and skates).  Members of this order have flattened bodies called disks, and whiplike tails that usually have poisonous spines at its base. These batoid fishes are commonly found throughout shallow tropical regions around the globe. They are ovoviviparous, being born after receiving nutrients and hatching in the female's uterus.


Manta rays are classified in the Family Myliobatidae. Photo credit: Wikimedia Commons.
Family: Myliobatidae
    Eagle rays, cownose rays, and manta rays make up the Myliobatidae family. They are considered the largest species of rays, reaching lengths up to 20 feet. Similar characteristics shared between the three different rays include having large dorsal fins, small/absent caudal fins, and two spiracles used for respiration located behind their eyes (Animal Diversity Web 2013).



Eagle rays, including spotted eagle rays are in the Genus Aetobatus. Photo credit: Wikimedia Commons.
Genus: Aetobatus
    The genus Aetobatus consists of eagle rays. Eagle rays have large pectoral fins resembling wings that are used to navigate through water, as seen in the photo to the right. They have flat teeth that aide in crushing and grinding their food, which consists mostly of gastropods and bivalves. Eagle rays often stray from coasts and swim out into the open ocean (Animal Diversity Web 2013).


Species: Aetobatus narinari
    Aetobatus narinari, commonly known as spotted eagle rays, are known for their vivid spotted dorsal colorations (seen in the photo below). They have rounded snouts and pointed pectoral fins. Their long tails can reach great lengths and have two to six poisonous spines at their base (Animal Diversity Web 2013). 


Spotted eagle rays have white spots and rings on the dorsal side of their body. Photo courtesy of Delphinusorca. What does Aetobus narinari mean in English?
    Spotted eagle rays were first described more than 200 years ago by an 18th century scientist named Euphrasen. The original name given to the eagle rays was Raja narinari, but was later changed to Aetobatus narinari. In native Indian the word narinari refers to stingrays, while the word Aetobatus is derived from two Greek words: aetos meaning eagle, and batis meaning ray (Silliman and Gruber 1999).

 

Continue on to learn about Habitat and Geography, or return to the Home page.

References