Sea Life of the Tasman Sea, Southern Australia and New Zealand | Sea Life, Islands and Oceania

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TASMAN SEA

Area of the Tasman Sea

The Tasman Sea is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. Named after the Dutch explorer Abel Janszoon Tasman, who was the first known person to cross it (in 1642), it is about 2,000 kilometers (1,200 miles) across, about 2,800 kilometers (1,700 miles) from north to south and has an area of 2.3 million square kilometers (890,000 square miles). The maximum depth of the sea is 5,943 meters (19,498 feet) . British explorer James Cook extensively navigated the Tasman Sea in the 1770s.

The Maori call the Pacific “Moana-Nui-o-Kiva” ("The Great Ocean of the Blue Sky"). The East Australian Current that flow southwards from the tropical Coral Sea, near the eastern coast of Australia is the most energetic circulation feature in the southwestern Pacific Ocean and is a primary means of heat transport from the tropics to the middle latitudes between Australia and New Zealand. The East Australian Current is a return of the westward-flowing Pacific Equatorial Current (Pacific South Equatorial Current).

At the margin between the Tasman and Coral seas. where the East Australian Current continues south in the western Tasman, a branch flows east called the Tasman Front towards the north of New Zealand with most continuing eastward above New Zealand into the South Pacific Ocean. The East Australian Current south of Tasmania also is diverted west in the Subtropical Front which collides with the western moving Subantarctic front of the Antarctic Circumpolar Current.

Sea Life in the Tasman Sea

The Tasman Sea is home diverse species, including large marine mammals like humpback whales, blue whales, sperm whales, and various dolphins and seals, along with numerous fish species such as blue grenadier and tuna. The region also supports seabirds, including albatrosses, sea turtles, and sharks, with some areas, like the South Tasman Sea, recognized as important foraging grounds for vulnerable species. A deep-sea research ship, the RV Tangaroa, explored the sea and found 500 species of fish and 1300 species of invertebrates and a tooth of a megalodon, the giant extinct shark.

Ocean currents around Australia

The Tasman Sea is on migratory routes and is a feeding ground for various whales, including humpback whales, blue whales, pygmy right whales, pilot whales and sperm whales. Southern right whales migrate to some places off the coast of New Zealand. Pygmy right whales are found in waters off New Zealand. They are sometimes mistaken for bowhead whales. Dolphins species include common dolphins, bottlenose dolphins, and dusky dolphins. Several seal species also inhabit the Tasman Sea.

The Tasman Sea is home to many shark and ray species, including great white sharks, tiger sharks, great hammerheads, blue sharks, spotted eagle rays and giant black rays. Other common fish include blue grenadier (hoki), Pacific saury, blue maomao, and various mackerels and wrasses. Varieties like the snowflake eel and leopard moray eel are also found in the sea.

spotted handfish

The Tasman Sea is home to ancient deep-sea coral communities and seabird populations, particularly albatrosses and petrels, with many species using it for foraging. Five out of seven sea turtle species, including the leatherback, loggerhead, and hawksbill, have been observed in the Tasman Sea. Longspine sea urchins and crown-of-thorns sea stars are examples of the invertebrates that inhabit the region.

Unusual Sea Creatures in The Tasman Sea

David Doubilet wrote in National Geographic: In the Tasman Sea off the east coast of Tasmania, cold nutrient-rich waters from Antarctica mix with warms water coming down from Australia, bringing creatures usually found at depth of 600 to 1,000 feet within range of scuba divers. [Source: David Doubilet, National Geographic, January, 1997]

The unique creatures found in the Tasman Sea's kelp beds include the multicolored foot-long weedy seadragons; silver fish called real bastard trumpeters; elephant fish with a bony proboscis it uses for digging shellfish; southern saw shark with a long saw-tooth snout is used to sense prey in the mud; the red velvet fish with highly venomous dorsal fin spines; various pieces of handfish that use their pectoral fins to walk and grasp; and great white sharks.

The king crabs found in the Tasman Sea are the world heaviest crab, weight up to 35 pounds. Unlike their North Pacific cousins, these creatures have short legs, thick claws and a fairly compact body. Found only in the waters off the coast of Tasmania and southern Australia, it moves lowly like "a sleepy sumo wrestler, by digging its claws into the bottom of the ocean,

Australia and Tasmania are home to eight species of handfish, which rarely swims but scavenges the bottom of shallow seafloors by walking with their armlike fins. In the 1980s, the spotted handfish was one of the most commonly seen fish in some coastal waters off of Tasmania. It numbers have drastically declined, perhaps as a result of pollution or predation by the northern Pacific sea star.

Pig Fish, found off Stewart Island in southern New Zealand, are strange creatures. First of all you can pick them up with you hands when they are wide awake (the only resistance they offer is an occasional grunt) and they can be "planted." Roger Grace, a scientist who has studied them, told National Geographic he was once holding one but needed to use both of his hands. He wasn't sure what to do with the fish so he dug a small hole in the sand and placed the pigfish inside it. The fish didn't move. Grace has planted whole "gardens" of pig fish and only a couple swam off. [Source: "New Zealand's Magic Waters" by David Doubiltet, National Geographic, October 1989]

Deep Sea Life in the Tasman Sea

A joint Australian-New Zealand exploration of submarine habitats around Norfolk and Lord Howe islands in the Tasman Sea off of Australia and New Zealand in 2003 towed trawling gear along the ocean floor, at a depth of 1,200 meters and pulled up more than 100 new species of fish and invertebrates. Among them were sea cucumbers, gulper eels, fangtooths, coffinfish, prickly dogfish, viperfish, slickheads, giant sea spiders, corals, and the fossilized tooth of an extinct megalodon — a shark many times the size of the great white. Franz Lidze wrote: There were spookfish (part squid, part fountain pen), whose snouts were equipped with electrical receptors to detect hidden prey; sponges as tall as ten feet; and humpback anglerfish — also known as black devils — that use bacteria to emit light through the long stalks sprouting from their heads. [Source: Franz Lidz, Smithsonian magazine, November 2015]

In January 2009, A team of U.S. and Australian researchers announced that had uncovered new marine life, including fiery red coral and purple-spotted sea anemones, in deep waters of the Tasman Sea off Tasmania. Associated Press reported: Sea spiders, a carnivorous sea squirt and a sponge with a waffle-like appearance were among the treasures the scientists saw more than 6,500 feet (2,000 meters) below the surface, Thresher said. The sea squirt, which stood 1.6 feet (half a meter) tall on the ocean floor, works like a venus flytrap, using a funnel-like appendage to collapse around prey that unwittingly brush past it. The team also found communities of marine life that have never been described in scientific literature, including gooseneck barnacles and millions of round, purple-spotted sea anemones. [Source: Kristen Gelineau, Associated Press, January 18, 2009]

Scientists also discovered corals more than 10,000 years old and will study them for clues on ancient climate data, and to help determine when coral reefs have existed south of Tasmania over the last several million years. Scientists who took part in the $2 million four-week expedition also found that most reef-forming coral deeper than 4,200 feet (1,300 meters) in the area were newly dead. Researchers will study samples of the coral to try and determine whether the creatures are dying because of ocean warming, disease, a rise in ocean acidity or some other reason

Kelp

Large kelp forest lie off the coasts of New Zealand, Australia, Tasmania, Japan and California. Stewart Island in New Zealand is home to kelp forests, New Zealand abalone, seal colonies and Great White sharks. Kings Island (50 minute flight from Melbourne) is remote island near Tasmania famous for its sea life.

Kelp is a kind of seaweed that forms long strips that hold rocks at the sea bottom with a claw-like fasteners that serves as anchors but provide no root like functions. Kelp need to anchored to the bottom of the sea or it washes away. There are 300 species of kelp. Most are not edible. Some of the edible species are brown when they are harvested but turn bright green when they are cooked.

Kelps are designed to live offshore in places with crashing surf. The have inflatable bladders that keep them afloat and strong, flexible leaves that move in the moving water without breaking. Some have slippery mucous coating to protect them from exposure to sun and air. Large masses of kelp are sometimes called kelp forests. A number of species that live among kelp are unique to kelp forests.

Kelps dominate the reefs of cool seas. Relatively little is known of their origins, Some think they originated 5 to 10 million years ago in the Northern Hemisphere when the northern seas were cool and full of nutrients, This theory is hard to prove because the soft tissues of kelps don’t mineralize into fossils very well. Studies of large abalone shells that feed primarily on kelp suggest that kelp first appeared in large amounts in the Northern Hemisphere about 5 million years ago.

Kelp Forests

Kelp forests provide habitat for a variety of invertebrates, fish, marine mammals, and birds. A kelp forest Many species of fish and marine mammals inhabit kelp forests for protection and food. In kelp forests, the most commonly found invertebrates are bristle worms, scud, prawn, snails, and brittle stars. These animals feed on the holdfasts that keep kelp anchored to the bottom of the ocean and algae that are abundant in kelp forests. Sea urchins will often completely remove kelp plants by eating through their holdfasts. Other invertebrates found in kelp forests are sea stars, anemones, crabs, and jellyfish. [Source: NOAA]

A wide range of fish can be found in kelp forests, many of which are important to commercial fishermen. For example, many types of rockfish such as black rockfish, blue rockfish, olive rockfish, and kelp rockfish are found in kelp forests and are important to fishermen.

A wide range of marine mammals inhabit kelp forests for protection and food. Sea lions and seals feed on the fish that live in kelp forests. Grey whales have also been observed in kelp forests, most likely using the forest as a safe haven from the predatory killer whale. The grey whale will eat the abundant invertebrates and crustaceans in kelp forests. One of the most important mammals in a kelp forest is the sea otter, who takes refuge from sharks and storms in these forests. The sea otter eats the red sea urchin that can destroy a kelp forest if left to multiply freely.

Kelp forests are a natural buffet for birds such as crows, warblers, starlings, and black phoebes which feed on flies, maggots, and small crustaceans that are abundant in kelp forests. Gulls, terns, egrets, great blue herons, and cormorants dine on the many fish and invertebrates living in the kelp. Kelp forests also provide birds with a refuge from storms.

Sea Dragons

The seadragons of South Australia are closely related to sea horses. Common sea dragon are purple and orange with tiny yellow polka dots on a maroon background. Leafy sea dragons looks more like pieces of seaweeds than animals. They along the edge of kelp beds sucking in food with their tumpetlike mouth.

Leafy Seadragon (Phycodurus eques)

Sea dragons are different from sea horses in a couple of ways — namely the way they move and use their tail. There are just two species — leafy and weedy, named for their form of camouflage — and both live in the temperate waters off Australia. Like seahorses they are an ambush predators that feeds by sucking small aquatic organisms rapidly into their mouth

The leafy seadragon is found only off of Western and Southern Australia. Living mainly in kelp forest off places like the Fleurieu Peninsula, near Adelaide, it can grow over 35 centimeters long and grows bony prongs from its spine, ribs and head that trail thin ribbons of camouflage. Little is known about it. It has been studied by marine biologist Greg Rouse, who has collected its DNA and found out that what was thought to be two species is actually one found over a large range. You can point one out to someone and they won’t see it, Rouse said, “I’m sure I swim over them all the time.” [Source: National Geographic]

Sea dragons have no teeth; they feed by way of suction. Their pipe-like terminal mouth has an intricate system of bones pulled by muscles to create a strong suction force that is directed at food. Their prey include mysid shrimp, sea lice, and larval fish. They sense using touch and chemicals usually detected with smell. Within the Syngnathidae family seahorses are Phycodurus and seadragons are Phyllopteryx.

Sea dragons are solitary animals that have no known predators. They are not sessile, but they are not very good swimmers, either. This is because their bodies are surrounded by protective dermal plates, which inhibit their mobility. Also, they lack a caudal fin, and therefore must rely on their ventral and dorsal fins for swimming. Because they are poor swimmers, each year a number of individuals are found washed ashore on the beaches of southern Australia. /=\

Weedy Sea Dragon

weedy sea dragon (Phyllopteryx taeniolatus)

Weedy sea dragons (Scientific name: Phyllopteryx taeniolatus) are also known as Common seadragons, and Lucas' sea-dragon. They are endemic to the waters off of the southern coast of Australia, with Individuals of this species sighted off the eastern coast of Australia in New South Wales, as far north as Port Stephens; along the southern coast; and up around the western coast of Australia as far north as Geraldton, West Australia. [Source: Anna Frostic, Animal Diversity Web (ADW) /=]

Weedy sea dragon can be found in rocky reefs, sea weed beds, sea grass meadows, and kelp gardens. In all of these areas, their leafy appendages provide protection by serving as camouflage against the sea weed. They are typically found at depths of 10 to 50 meters (33 to 164 feet) in waters that must be between 12 and 23 degrees Celsius (53 to 73 degrees F)

The weedy sea dragons can reach 45 centimeters in length and has a narrow body with a long, tubular snout. According to Animal Diversity Web: It has two spines above its eye, one spine in front of the eye, and a varying number of leafy appendages, either paired or single, along its body. These purple appendages have a black border, and provide the fish camouflage in its habitat because they resemble floating seaweed. The bodies of these fish are usually red with yellow spots and seven purplish blue stripes near the head. Weedy sea dragons are not sexually dimorphic and have no subspecies, but do have a close relative: Phycodurus eques, the leafy sea dragon. The leafy sea dragon is found in the same geographic range, and differs in appearance only because it has many more appendages.

While it is not known at what age sea dragons reach sexual maturity, their reproductive strategies are well documented. Like their relatives the sea horses, the male sea dragons brood the eggs. When a male is ready to receive the eggs, which he indicates by wrinkling the lower half of his tail, the female deposits about 250 ruby colored eggs onto his brood patch. The brood patch is made of tiny cups of blood-rich tissue, and each cup holds and nourishes one egg. After eight weeks, the eggs hatch over a period of a couple days. After hatching, the young sea dragons spend two or three days in the yolk sac of the egg, where they continue to be nourished. After the young leave the yolk sac, they feed on copepods and rotifers, although only 60-120 of them will survive, while the others fall prey to sea anemones. The season of breeding is August through March, and during this time the males brood two batches of eggs. The young receive no parental care after they hatch because they are released into the external environment.

Weedy Sea Dragon, Humans and Fish Farming

leafy sea dragon (Phycodurus eques)

Weedy sea dragon have been used in Asian medicines and one reason why divers brave great white sharka to scuba diving off the coast of southern Australia, Weedy sea dragons are threatened by aquarium collectors and Oriental herbalists, who can sell their dried and powdered bodies for up to $200/gram. They are also killed by pollution and fertilizer run-off in their shallow, coastal habitats. Because of these threats, weedy sea dragons are a legally protected species in both New South Wales and Tasmania. On the IUCN ) Red List they are categorized as near threatened.. On CITES they have no special status

Juliet Eilperin wrote in the Washington Post: Aquarists have made some breakthroughs with The Aquarium of the Pacific in Long Beach, Calif., became the world’s first to breed weedy sea dragons in 2001, from a progenitor named “Big Daddy,” but it only repeated that feat once, in 2003. Perry Hampton, the aquarium’s vice president of husbandry, said his team has mimicked the sea dragons’ natural environment through water temperature and light exposure, but they can’t force the animals to mate. Scripps professor Greg Rouse received a $300,000 grant to launch the first-of-its-kind sea-dragon breeding pilot program with the Birch Aquarium. [Source: Juliet Eilperin, Washington Post April 15, 2012]

Australian Ghostsharks (Elephant Fish)

Australian ghostsharks (Callorhinchus milii) are chimaera (Holocephali) — a type of cartilaginous fish that are not sharks or rays but are similar to them and related to them and are believed to pre-date them on the evolutionary tree. Also known as elephant fish, ghost sharks, whitefish, plough-nose chimaera, silver fish, elephant sharks and makorepe (in Maori), Australian ghostsharks are unique and important to our understanding of the evolution of all back-boned animals. [Source: Wikipedia]

In January 2014, Nature published research on the Australian ghostshark genome that indicated they lacked a single gene family that regulates the process of turning cartilage into bone, and showed a gene duplication event was behind the creation of bony vertebrates (which includes all mammals, birds and reptiles and amphibians and most fish). The genome of Australian ghostsharks is estimated to be 910 megabases long, the smallest among all the cartilaginous fishes and one-third the size of the human genome (3000 Mb). Because cartilaginous fishes are the oldest living group of jawed vertebrates, the Australian ghostshark genome serves as a useful reference genome for understanding the origin and evolution of vertebrate genomes including humans.

Australian ghostshark

Australian ghostsharks are the only chimaera living today that don’t live in really deep water and among the most primitive and slow-to-evolve organisms on earth. Analysis of living sharks, rays and chimaeras suggests that by around 450 million years ago, around the time that the first plants invaded the land, chimaeras had already split from what became the shark-ray group. As there are no fossils of these animals from this period of time, this is based solely on the DNA and molecular evidence of modern sharks and chimaeras. So far, genetic evidence has shown that humans actually share more similarities with these ancient sharks, rays and chimarea than they do with more modern bony fish. [Source: NOAA],

Australian ghostsharks have a fairly limited range. They are found off southern Australia, including Tasmania, and south of East Cape and Kaipara Harbour in New Zealand, at depths of 0 to 200 meters (0 to 656 feet). They prefer continental shelves with temperate waters and have been found at depths of 600 meters (1968.5 feet). Females seasonally move to shallower waters to lay eggs. It has been hypothesized that the New Zealand population and the Australian population may actually be separate species. [Source: Kayla Boyes, Animal Diversity Web (ADW) |=|]

Australian ghostsharks are not endangered or threatened and relatively abundant throughout their range. They are designated as a species of Least Concern on the International Union for Conservation of Nature (IUCN) Red List. They Australian ghostsharks are caught both commercially and recreationally and are often marketed as "whitefish." They are often used as the fish in “fish and chips” in Australia and New Zealand. There are catch limits and commercial fishing reports indicate that stocks are stable. There have been some reports though that some areas in Australia have been overfished and recreational fishing takes breeding females near shore. Australian ghostsharks are preyed upon by larger fish and sharks such as the broadnose sevengill sharks. Their primary defense is their camouflage coloration.

Australian Ghostshark Characteristics and Diet

The name of Australian ghostsharks is a misnomer. They are not sharks. They are or are related to type of cartilaginous fish known as a “chimaera” and belongs to a subclass called Holocephali which diverged from the shark lineage more than 450 million years ago. They are sometimes called “plownose” chimaeras because of their bizarrely shaped snout. According to The Conversation: Analysis of their genome has shown the species changes at a veritable snail’s pace. In fact, it has the slowest evolving genome of all vertebrates, with its DNA almost imperceptibly altered over hundreds of millions of years.. Alice Clement, Research Associate in the College of Science and Engineering, Flinders University, The Conversation October 10, 2022]

Australian ghostshark range: red lower right

Australian ghostsharks range in weight from three to four kilograms (6.6 to 8.8 pounds) and range in length from 10 centimeters to 1.2 meters (four inches to four feet). Their lifespan in the wild is up to 15 years based on a tagged individual. Dorsal fin spine growth increments indicate maximum size is reached at about nine years. Sexual Dimorphism (differences between males and females) is present: Females are larger than males. [Source: Kayla Boyes, Animal Diversity Web (ADW) |=|]

Australian ghostsharks are silver in color, and often are covered in distinct dark markings — irregular dark blotches on the sides and fins. They have a distinctive flexible, trunk-like projection at the tip of the snout — the source of their common elephantfish. Other characteristics include an elongated body, presence of an anal fin, an arched caudal fin, and two widely spaced dorsal fins. The first fin has a serrated spine at its front, and the second is relatively tall with a short base compared to other chimaera species. Mature males exhibit a unique head clasper, an erupted tenaculum on a pre-pelvic clasper, and large calcified pelvic claspers.

Unlike all other chimaera species, Australian ghostsharks have a very well developed rectal gland. The rectal gland helps the regulating osmotic conditions in the body of the fish, which allows them deal with water salinity changes. It is thought that migrating and mating Australian ghostsharks may encounter water with varying salinity, allowing successfully inhabit more shallow coastal waters. Other chimera species don’t have such a developed rectal gland and are found in deep water habitats, where they don’t have to deal with salinity difference.

Australian ghostsharks are carnivores (eat meat or animal parts) and mostly molluscivores (eat mollusks. They primarily feed on mollusks and shellfish including the clam species Maorimactra ordinaria and also prey on marine worms and aquatic crustaceans. Australian ghostsharks probe the ocean floor substrate with the plow-shaped protrusion on their snout to find food.

Australian Ghostshark Behavior, Reproduction and Development

Australian ghostsharks are motile (move around as opposed to being stationary) and migratory (make seasonal movements between regions, such as between breeding and wintering grounds). Seasonal migration for mating has been well documented in shallow coastal areas that are often populated by people. There is no evidence of territorial behavior (defending an area within the home range) by these fish. Australian ghostsharks are regarded as a solitary species. However, fishermen report separate catches of males and females in the same areas suggesting the sexes segregate in the wild when not reproducing. Australian ghostsharks communicate with vision and chemicals usually detected by smelling, and sense using vision, vibrations, electric signals and chemicals. They have large eyes, and use their unique “trunk” — which covered with sensory pores that can detect movements and small electrical impulses — for perception, which allows them to find prey hidden in the ocean bottom. [Source: Kayla Boyes, Animal Diversity Web (ADW) |=|]

Australian ghostsharkss are oviparous, meaning they produce eggs that hatch outside the body. They engage in internal reproduction in which sperm from the male fertilizes the egg within the female and employ sperm-storing (producing young from sperm that has been stored, allowing it be used for fertilization at some time after mating). Australian ghostsharks engage in seasonal breeding — during the southern hemisphere summer and early autumn months. Fertilization and spawning occur between February and May. The number of offspring ranges from one to two. Females reach sexual or reproductive maturity at four to five years and males do so at three years. [Source: Kayla Boyes, Animal Diversity Web (ADW) |=|]

Males have a pair of retractable head claspers, pre-pelvic claspers, and calcified claspers to help hold the female during copulation. The head and pre-pelvic claspers are unique to Australian ghostsharks and are not found in other species of sharks, rays or chimaera. Female Australian ghostsharks have a “sperm pouch” to store spermatic material. Actual mating behavior has not been observed. During the breeding season adults migrate to the shallower waters of bays and estuaries to mate. Large, flat egg-cases containing a single embryo are deposited on muddy or sandy substrate. When released, egg-cases are yellow, but slowly turn brown or black. A female lays two eggs about a week apart that develop for six to eight months. Embryos feed on the yolk until they hatch.

Embryonic development is divided into 36 stages followed by hatching, which are based on morphological characteristics such as to length, amount of pigmentation, eye development, and head flexure. According to Animal Diversity Web: Rostral bulb (snout) size is used primarily when classifying embryos from stages 17-29 while tail length, gill filament size, and snout development are used to identify more mature embryo specimens. While early characteristics are more notable from one stage to the next, later stage assignment is often made more complex by less distinction between the characteristics of each stage.

Hatchlings are fully developed and look just like miniature adults upon emergence from the egg case. They are independent. There is no parental involvement in the raising of young after eggs are laid. From the time they hatch until they reach a length of approximately 50 centimeters, Australian ghostsharks grow in a linear fashion. At this length males are mature. However, the female growth then accelerates to about twice the rate of males until they reach sexual maturity at about 70 centimeters in length.

Short-Tail Stingrays (Giant Black Rays)

Short-tail stingrays(Bathytoshia brevicaudata, Dasyatis brevicaudata) are also known as giant black rays, smooth stingrays, giant stingrays, New Zealand short-tail stingarees, short-tailed stingarees, shorttail black stingrays, smooth short-tailed stingrays and Schreiners rays. One of the largest stingrays in the world, they are heavy-bodied and reach 2.1 meters (6.9 feet) across and 350 kilograms (770 pounds). They are a common species of stingray in the family Dasyatidae and occurs off southern Africa, southern Australia and New Zealand, from the intertidal zone to a depth of 156 meters (512 feet). These rays are mostly bottom-dwelling and can be found across a range of habitats from estuaries to reefs, but also frequently will swim into open water.. They are not aggressive, but are capable of inflicting a lethal and painful wound with their long, venomous stinger. A Short-tail stingray was responsible for killing Steve Irwin ("The Crocodile Hunter") in 2006.

Short-tail stingrays

Short-tail stingrays are bottom-dwellers in temperate waters. Toccurs offshore of southern Africa at depths between 180 and 480 meters (590 and 1,570 feet), and off southern Australia and New Zealand, from the intertidal zone to a depth of 156 meters (512 feet). They are found on the seafloor in harbors, coastal bays, large inlets, and coastal reefs. Away from the coasts, they have typically been found at depths around 150 meters (495 feet). Sometimes they are found in underwater caves and under large overhangs. Research of gene flow in short-tail stingrays indicates they do not migrate long distances; traversing large expanses of open water appears limit mobility for mating and nursing. There are large breeding grounds and nurseries on the northwestern side of Poor Knights Island, New Zealand. [Source: Robert Krebs, Animal Diversity Web (ADW) |=|]

Short-tail stingrays are not endangered or threatened. They are fairly abundant in their range and ar designated as a species of least concern on the International Union for Conservation of Nature (IUCN) Red List. They are often caught accidentally by commercial and recreational fisheries throughout their range, and usually survive long enough to be released. In 1994, short-tail listed as threatened in some areas due to overfishing. Boats are also capable of harming short-tail stingrays. The Main threats to short-tail stingrays are predators, like sharks and orcas (killer whales) and commercial fishing. Stingrays, in general, use lateral lines to detect water movement and avoid predation. Short-tail stingrays are well camouflaged. There are various laws and regulations that protect these stingrays. Measures are in place to contrl tourism at the Poor Knights Island breeding area. Attempts at captive breeding have had problems such stingrays killing their mates during reproduction.

Short-tail stingrays usually do not attack people and they are often encountered by divers and snorkelers. Some people eat them. Short-tail stingrays have venomous tails that can be lethal to humans, but they only sting as a defensive measure. This can happen if you accidentally step on one. Their stingers are made of cartilage and are shaped like a tapered whip with doubly-serrated sides. These tails can reach up to 30 centimeters (one foot) in length. The venom consists mainly of neurotoxins (phosphodiesterases, 5’ nucleotidases, serotonin) and other proteins. Symptoms of the venom include weakness, severe pain, necrosis, nausea, headaches, hypotension, fasciculation, dysrhythmia, and vertigo (because of the neurotoxins). The respiratory and circulatory systems are at the biggest risk when this venom enters the body. Common measures for treating a stingray victim are use of opioids for pain relief and then surgery. A hot water bath, saline solution, and surgical removal of fragments from the stinger are usual steps for patients. Using heat reduces toxin potency. Steve Irwin died because the stingray’s barb went through his chest and a lung and penetrated his heart, causing heart damage and massive blood loss. The attack occurred because the stingray felt cornered and acted in self-defense when Irwin's shadow fell over it.

Short-Tail Stingray Characteristics and Diet

range of short-tail stingrays

Short-tail stingrays reach weights of 350 kilograms (770.93 pounds) and range in length from 1.1 to 4.3 meters (3.6 to 14.1 feet) and can be three meters (10 feet) wide. The oldest short-tail stingray recorded in the wild was 30 years old. Some sources list their age in captivity as being up 70 to 80 years. Short-tail stingrays are closely related to and look similar to smaller pitted stingrays (Dasyatis matsubarai) of the northwestern Pacific. Sexual Dimorphism (differences between males and females) is present among Short-tail stingrays: Males are larger than females. Males are the ones that weigh 450 kilograms and are 4.3 meters long. Females are generally around 1.1 meters wide and weigh around 45 kilograms (100 pounds). [Source: Robert Krebs, Animal Diversity Web (ADW) |=|]

Short-tail stingrays are grey on their back sides and white on their bottom sides. Their bodies are similar to an oblong disc or a blunt diamond shape. Their diamond-shaped pectoral fin disc — their bidy — is characterized by a lack of dermal denticles even in adults, and white pores beside the head on either side. The bodies of short-tail stingrays are smooth, except for their tails, which are skinny and serrated. The body can have colors as well as dark grey or black with rows of white spots along each wing.

The tails of short-tail stingrays average 22 centimeters (nine inches) in length, with a thick base that narrows out. Their tails are venomous. They can have multiple venomous tails, but there is always one main tail that can grow up to 30 centimeters (one foot). The tails are made of cartilage and is usually shorter than the disc and thick at the base. The tail is armed with large tubercles and a midline row of large thorns in front of the stinging spine which has the dorsal and ventral fin folds behind. Short-tail stingrays have 10 gill slits, which are positioned in diagonal lines and form an incomplete "V" shape. The gill slits closest to their mouths are the most distal. They also have other forms of respiratory holes, known as spiracles, located behind and adjacent to their eyes. There are usually 25 series of teeth and about 45 to 50 rows of teeth across their jaw lines.

Short-tail stingrays are technically omnivores (eat a variety of things, including plants and animals) and primarily carnivores (eat meat or animal parts) but are recognized as piscivores (eat fish) and molluscivores (eat mollusks). They eat a variety of crustaceans, cephalopods, arthropods, and small bony and non-bony fish. They eat boyh burrowing and midwater species. as well as smaller cnidarians and sometimes they consume plants.

Short-Tail Stingray Behavior, Senses and Communication

Short-tail stingrays are motile (move around as opposed to being stationary), nomadic (move from place to place, generally within a well-defined range) and migratory (make seasonal movements between regions, such as between breeding and wintering grounds). They are widely regarded as diurnal (active mainly during the daytime) but rod-to-cone ratio suggests that they may be active nocturnally (at night) as well. They tend to stay in certain coastal areas near where they are born, but have been frequently found to migrate to other coasts within temperate waters. Short-tail stingrays are defensive by nature and harmless unless they feel threatened. They can defensively sting with their venomous tail or tails.

Short-tail stingrays do not have a specific home range and do not defend a territory. They tend to remain within a relatively limited area throughout the year, preferring deeper waters during the winter. They are not known to perform long migrations. Large aggregations of rays form seasonally at certain locations, such as in the summer at the Poor Knight Islands off New Zealand. Both birthing and mating have been documented there.

Short-tail stingrays sense and communicate with vision, touch, vibrations electric signals and chemicals usually detected by smelling. Their eyes are small and medial lateral to each other. The ratio of rods to cones is 10:1 in their retina. They have oval-shaped nostrils on their anterior sides, about 13 centimeters from the ventral view to the mouth. Short-tail stingrays have pores and canals, or lateral lines, that consist of receptors that have a mechano-tactile function. Located on the ventral sides of the ray, these lateral lines mainly detect deal vibrations of prey they are also capable of generating electricity for communication, defense, prey location and detecting partners. They also use their receptors to detect water movement around them.

Short-Tail Stingray Mating, Reproduction and Offspring

Short-tail stingrays are ovoviviparous, meaning that eggs are hatched within the body and young are born live. Temperature and daylight are triggers to the reproduction cycle of short-tail stingrays; if those are altered, then reproduction gets delayed. Closely-related rough-tail stingrays, black stingrays and southern stingrays mate and give birth frequently. The breeding months span from late spring to autumn. The number of offspring for rough-tail stingrays is typically six to 10 offspring. When mating, male and female short-tail stingrays interact via tactile communications. Male claspers are involved in internal reproduction in which sperm from the male fertilizes the egg within the female. |=| [Source: Robert Krebs, Animal Diversity Web (ADW) |=|]

When mating, male short-tail stingrays swim upside down, underneath females, and bite the discs of females. Then male stingrays insert their claspers into the cloacae of females, and also nudge their abdomens. Female southern stingrays mate with several males (polyandrous), one at a time. Males swim behind a single female in a cluster. One male grab onto the body of the female and copulate with her.

Short-tail stingrays are lipid histotrophs, meaning mothers produce milk for their offspring in the uterus. Offspring are born either inshore or offshore, on the outer shelf and uppermost slope; offspring travel straight to the sea floor after birth. Sometimes they are birthed in caves. Mostly they are found in sandy bays, estuaries, harbors, or at rocky reefs . There is no parental care after birth. Newborns are born live and independent and stay within the area of seafloor in which they were born and migrate as they age and grow larger. After closely-related round stingray pups are born, they remain within 180 meters of land. When the offspring are old enough (when their body growth has ceased), they start traveling farther out, where other adults are, and search for larger prey items. Short-tail stingray offspring have about 36 centimeters disc width at birth. Juveniles disc widths are 1.0 to 1.5 meters. It is believed to be that exhibit indeterminate growth (they continue growing throughout their lives)

Image Sources: Wikimedia Commons

Text Sources: Animal Diversity Web animaldiversity.org , National Geographic, Live Science, Natural History magazine, Australian Museum, David Attenborough books, Australia Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The Conversation, The New Yorker, Time, BBC, CNN, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated September 2025