Chrysaora achlyos
Encyclopedia
The black sea nettle sometimes informally known as the "black jellyfish" due to its dark coloration, is a species
of jellyfish
that can be found in the waters of the Pacific Ocean
. Its range is thought to be from Monterey Bay
in the north, down to southern Baja California
and Mexico
, though there are reports of sightings as far north as British Columbia
. It is a giant jellyfish, with its bell measuring up to 1 m (3 ft) in size, and its oral arms extending up to 6 m (20 ft) in length. Despite its size and occasional proximity to Pacific coastal cities, the Black sea nettle was only recognized and scientifically described as a separate species in 1997, though misidentified pictures of the jellyfish had been taken in 1925. It has the scientific distinction of being the largest invertebrate discovered in the twentieth century.
While sightings have been rare, when they are seen it is often as part of a massive swarm of the creatures, such as those that occurred in surface waters off the coast of Baja California and southern California in 1989, 1999 & 2010.Interestingly, these sightings seem to coincide with incidents of red tide
s, which consist of the zooplankton
that Black sea nettles feed upon.
The sea nettle is radially symmetrical
, marine, and carnivorous
. Its mouth
is located at the center of one end of the body, which opens to a gastrovascular cavity
that is used for digestion
. It has tentacle
s that surround the mouth to capture food. Nettles have no excretory or respiratory organ
s.
. They generally feed on zooplankton and other jellyfish. Nettles immobilize and obtain their prey using their stinging tentacles. After that, the prey is transported to the gastrovascular cavity where it is digested.
s capable of killing smaller prey or stunning perceived predators. On humans, this will most likely cause a nonlethal, but painful stinging sensation which can last for forty minutes.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of jellyfish
Jellyfish
Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...
that can be found in the waters of the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. Its range is thought to be from Monterey Bay
Monterey Bay
Monterey Bay is a bay of the Pacific Ocean, along the central coast of California. The bay is south of San Francisco and San Jose, between the cities of Santa Cruz and Monterey....
in the north, down to southern Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
and Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, though there are reports of sightings as far north as British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
. It is a giant jellyfish, with its bell measuring up to 1 m (3 ft) in size, and its oral arms extending up to 6 m (20 ft) in length. Despite its size and occasional proximity to Pacific coastal cities, the Black sea nettle was only recognized and scientifically described as a separate species in 1997, though misidentified pictures of the jellyfish had been taken in 1925. It has the scientific distinction of being the largest invertebrate discovered in the twentieth century.
Red tide
Red tide is a common name for a phenomenon also known as an algal bloom , an event in which estuarine, marine, or fresh water algae accumulate rapidly in the water column and results in discoloration of the surface water. It is usually found in coastal areas...
s, which consist of the zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
that Black sea nettles feed upon.
The sea nettle is radially symmetrical
Symmetry
Symmetry generally conveys two primary meanings. The first is an imprecise sense of harmonious or aesthetically pleasing proportionality and balance; such that it reflects beauty or perfection...
, marine, and carnivorous
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
. Its mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
is located at the center of one end of the body, which opens to a gastrovascular cavity
Gastrovascular cavity
Gastro vascular cavity, as the name indicates, functions in both digestion and the distribution of nutrients and particles to all parts of the body...
that is used for digestion
Digestion
Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones....
. It has tentacle
Tentacle
A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...
s that surround the mouth to capture food. Nettles have no excretory or respiratory organ
Organ (anatomy)
In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...
s.
Feeding habits
Black sea nettles are carnivorousCarnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
. They generally feed on zooplankton and other jellyfish. Nettles immobilize and obtain their prey using their stinging tentacles. After that, the prey is transported to the gastrovascular cavity where it is digested.
Defense mechanisms
Each nettle tentacle is coated with thousands of microscopic nematocysts; in turn, every individual nematocyst has a "trigger" (cnidocil) paired with a capsule containing a coiled stinging filament. Upon contact, the cnidocil will immediately initiate a process which ejects the venom-coated filament from its capsule and into the target. This will inject toxinToxin
A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...
s capable of killing smaller prey or stunning perceived predators. On humans, this will most likely cause a nonlethal, but painful stinging sensation which can last for forty minutes.