Identifying Shark and Ray Eggcases - Marine Dimensions (2024)

Identifying Shark and Ray Eggcases - Marine Dimensions (1)

The eggcases of egg-laying sharks and rays (also known as mermaids’ purses) can be found washed up on many coastlines around the world, and the size and shape of the purse can be used to distinguish each species. For example, skates and rays can be instantly recognized by a pair of horns positioned at either end of the central capsule or case. These help to anchor the purse to the soft shore sediment. Catshark eggcases possess curly tendrils that are used to attach the purse to seaweed.

The structure of the capsule can also be used to identify some species. For example, the Thornback Ray eggcase has a narrow ridge or keel along the edge of its capsule.

If you’re interested in learning more, check out our article on mermaid’s purse identification. It goes into a lot more depth on how to identify species from all around the world.

Identifying Shark and Ray Eggcases - Marine Dimensions (2024)

FAQs

Identifying Shark and Ray Eggcases - Marine Dimensions? ›

For example, skates and rays

skates and rays
Skates are cartilaginous fish belonging to the family Rajidae in the superorder Batoidea of rays. More than 150 species have been described, in 17 genera. Softnose skates and pygmy skates were previously treated as subfamilies of Rajidae (Arhynchobatinae and Gurgesiellinae), but are now considered as distinct families.
https://en.wikipedia.org › wiki › Skate_(fish)
can be instantly recognized by a pair of horns positioned at either end of the central capsule or case. These help to anchor the purse to the soft shore sediment. Catshark eggcases possess curly tendrils that are used to attach the purse to seaweed.

What is the difference between shark and ray eggs? ›

Skates and rays tend to have more elongated pouches with horn-like protrusions at each end. Shark egg cases often have spiral coiled tendrils which can be lodged into crevices or attached to underwater structures such as rocks, seaweed, or coral reefs.

How do you identify a fish egg case? ›

Eggcase elongated (length approximately 2.5 times the width). Has curled tendrils on each corner or short horns (depending on species). Eggcase squarer/rectangular in shape and (if not broken) has a horn extending from each corner of the capsule (more pronounced in some species).

How to identify a mermaid's purse? ›

Nicknamed mermaid's purses, the pillowy egg cases found in our area are black and rectangular, with four “horns” on each corner. It is theorized that the protrusions help anchor the egg cases into vegetation and the sandy seafloor. Depending on species, they may incubate from 2-15 months before hatching.

What does a shark egg sac look like? ›

Egg cases without a fibrous outer layer can be striated, bumpy, or smooth and glossy. With the exception of bullhead shark eggs, egg cases are typically rectangular in shape with projections, called horns, at each corner. Depending on the species, egg cases may have one or more tendrils.

What is the most obvious difference between sharks and rays? ›

Rays first appear in the fossil record about 200 million years later than the first sharks, and are thought to have evolved from flattened shark species. One of the most obvious differences with sharks is that the pectoral fins of rays and skates form a large disc, which starts from the back of the skull.

What do rays eggs look like? ›

Eggcase horns and tendrils

If the egg has been produced by a skate or ray, you'll generally see two spikes or horns at either end of the central capsule (where the embryo is housed). These are used to anchor the purse in the soft seafloor nursery habitat of the flat sharks and rays.

What to do if you find a shark egg on the beach? ›

If a live embryo is inside, put the eggcase back in the sea or a deep rockpool and try to anchor it down. If it is a skate eggcase try and weigh down the horns, with catshark eggcases try and tie the tendrils around something so it doesn't wash ashore again. Empty eggcases are not known to have any secondary purpose.

How do you measure the diameter of a fish egg? ›

Mullet fish egg diameter measurement have done by taking part in the anterior, posterior, and middle of the gonads, each totaling 30 items then their diameters measured using a microscope eyepiece with a magnification of 40 x.

What are fish egg sizes? ›

Diameter of egg range from 0.5 to 5.5 mm. The largest number of eggs is below 1 mm diameter in size, followed by ones whose diameter ranges between 1 and 1.5 mm, then from 1.5 to 2 mm, and the smallest percentage of pelagic eggs have a size larger than 2 mm.

What should you do if you find a mermaid's purse? ›

If you find an eggcase, the first thing to do is to try and identify which species it comes from. To do this you need to look at the size, shape and key features of the eggcase, such as a particular texture or pattern. There is an eggcase ID guide and a step-by-step ID Key to help you do this.

How to identify shark eggs? ›

Catshark eggcases possess curly tendrils that are used to attach the purse to seaweed. The structure of the capsule can also be used to identify some species. For example, the Thornback Ray eggcase has a narrow ridge or keel along the edge of its capsule.

What do horn shark eggs look like? ›

Each of these Horn Shark eggs contain a single embryo. Females lay these screw-like spiral cases, which they then tightly wedge into crevices.

How do you identify a mermaid purse shark egg case? ›

Different types of egg cases

The general appearance of a mermaid's purse is a black or brown leathery pouch with either tendrils or horns coming off each or either end. For catsharks the pouch will tend to be more rounded and have long spindly tendrils, which can often get wrapped around in seaweed or other egg cases.

How big is a shark egg? ›

Egg-laying sharks

Usually the eggs are quite large, 5 to 25 cm long. They contain a lot of yolk to ensure that the embryos are richly supplied with nutrients.

What does a bull shark egg look like? ›

Other species, including the bullhead shark, will produce spiral-shaped eggs.

What is the difference between rays and sharks? ›

While sharks have a body shape like other fish, most skates and rays have flattened bodies that are wing-like, helping them glide effortlessly through the water.

What are some differences between sharks and rays? ›

Like sharks, rays don't have a swim bladder, but unlike sharks, they move their pectoral fins when they swim. They also must stay in motion constantly or they will sink! Electric rays make their own electricity! They have organs on either side of their heads that can deliver a shock of up to 200 volts!

Do sharks and rays lay eggs? ›

Oviparous reproduction is used by about 30 % of sharks and rays in the world. After mating they will lay their eggs covered by a leathery case on the sea floor or attached to reefs.

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