THE ANIMAL FILES

Southern stingray

Hypanus americanus

Eyes look upward while water enters through openings behind them.

The southern stingray is a flattened, diamond-shaped ray that uses the seabed for resting and foraging. Its mouth lies underneath, while eyes and spiracles sit above, allowing different functions on the two body surfaces.[1]

Follow the evidence ↓
Southern stingray
Image: Pauline Walsh Jacobson · Commons · CC BY 4.0
Breathing inlet
Spiracles behind the eyes[1]
Food
Worms, crustaceans, small fish and bivalves[1]
Young
Born live[1]

Breathing while partly buried

Water enters the spiracles above and exits through gill openings below. This route bypasses the mouth, useful when the lower surface lies against sediment or the body is partly buried.[1]

Uncovering a hidden meal

The ray can disturb sediment with water jets or fin movements, exposing concealed prey. Undulating pectoral fins also propel it across the bottom. Movement can therefore serve both travel and food discovery.[1]

Development inside the mother

Embryos first draw on yolk and later receive uterine secretions before live birth. Young then begin independent life rather than receiving prolonged parental rearing. Internal development does not imply a placental connection like that of many mammals.[1]

A COMMON MIX-UP

Must a bottom-resting ray breathe through a sand-covered mouth?

No. The upper spiracles provide a route for water to reach the gills without entering through the mouth.[1]

TRY A LITTLE REASONING

Why place a breathing inlet on the upper surface?

Reveal the explanation

It remains accessible while the lower surface is close to the bottom, helping separate breathing intake from contact with sediment.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Southern stingray (fixed revision; adapted and translated)
  2. NCBI Taxonomy — Hypanus americanus (identity and classification)

Last fact check:

One discovery leads to another

Giant oceanic manta rayThe curled head fins can unfold to guide food-bearing water inward.Mobula birostris ↗Spiny dogfishA shark’s spines are not its teeth.Squalus acanthias ↗Blue sharkBlue above, pale below: an ocean swimmer has more than one colour.Prionace glauca ↗