Rays

Question 1

What are the ecosystem services provided by rays?

Answer 1

1. EAT - BENTHIC rays feed on bottom-dwelling species (crabs, snails, clams, oysters etc). Mantas FILTER plankton from the water.
2. PREY - SHARKS and large fish prey on smaller stingrays in tropical waters. Big sharks prey on larger ray species.
3. POOP - cycles NUTRIENTS and distributes them throughout the ecosystem.

Question 2

What are threats to rays?

Answer 2

Rays are caught using SPEARS and baited HOOK & LINES. The meat is consumed and the gill rakers of larger rays (mantas and mobulas) are dried for traditional medicine.
Rays are caught as BYCATCH in commercial fishing, and affected by OVERFISHING, HABITAT DESTRUCTION, CLIMATE CHANGE and other ANTHROPOGENIC PRESSURES, causing serious population declines.

Question 3

How do rays and skates fertilise gametes?

Answer 3

Rays and skates have separate sexes and fertilisation is INTERNAL 0 males transfer sperm to females which give birth to LIVE YOUNG or lay large leathery EGGS.

Question 4

What are the male reproductive organs of rays and how are they used?

Answer 4

Male rays have two CLASPERS (external sex organs) located beneath the body. A male uses one of his claspers to transfer sperm into the CLOACA (opening) of the female.

Question 5

How do female rays carry fertilised gametes?

Answer 5

In most species, the female carries the young within her body for 9 months before giving birth to up to 15 LIVE YOUNG rays. They swim and go hunting with their mother.
In manta rays, only 1 live pup is produced.
Egg-laying species lay eggs (mermaids purses) which hatch to juvenile rays that look like small adults. They grow slowly, only 1 in 10 juveniles survives to sexual maturity around 8 years. Lifespan is around 30 years.

Question 6

What are the 3 colour morphs of manta ray species?

Answer 6

1. CHEVRON - ‘regular’ colouration. Dorsal side is black with white on the head and tips of the fins; ventral side is white with spot markings.
2. MELANISTIC - black. Dorsal side is completely black; ventral side is black with white patches.
3. LEUCISTIC - white/pale but not albino. Dorsal and ventral sides are white with darker patches.