Cnidarians | Cnidaria

Cnidarians or Cnidaria are mostly found in marine environments. However, some species are found in freshwater bodies. They include sea anemones, corals, and jellyfish. They are identified by the cnidocyte cells for capturing prey. Their body is sandwiched between two epithelium cells and composed of a living jelly-like substance called mesoglea. Cnidarians mainly prey on planktons, parasites, and small animals like turtles and sea slugs. Adult cnidarians have no heads and would appear as free-swimming medusae or sessile polyps. They have tentacles around their edges and inner mouths and reproduce either sexually or asexually.

What do cnidarians use for defense?

Cnidarians are aquatic animals with two body forms (the ectoderm and endoderm separated by a mesoglea). To capture prey or even defend themselves, cnidarians have unique and well-developed specialized cells in their mouths and tentacles for stinging attackers. These cells, called cnidocytes, have toxins that are released when their body is touched.

How do cnidarians reproduce?

Sexual and asexual reproduction are the forms of reproduction seen among cnidarians. Besides, some are hermaphrodites — capable of producing both eggs and sperms at the same time. However, asexual reproduction is the most common in this species. Sexual reproduction may occur only in one phase of a cnidarian’s life cycle.

Do cnidarians have brains?

What cnidarians have are diffuse nets of nerves that coordinate messages around their bodies. Research shows that these nets of nerves are just as complex as that of human beings. In addition, some like jellyfish, have no heart or eyes. Most cnidarians also have a transparent body covered in a chitinous exoskeleton.

Cnidarians Guides
Browse through our curated Cnidarians Guides for additional categorizations, tips, details, variations, styles, and histories of Cnidarians. Guides provide additional insights into the unique properties and shared relationships between elements.
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2.36”-4.33” | 6-11 cm
5”-9.84” | 12.7-25 cm
17.7”-35” | 45-89 cm
6-18 months
Atlantic Sea Nettle
11.000
25.000
89.000
1.50
300
3D
Atlantic Sea Nettle
.79”-6.7” | 2-17 cm
.79”-6.7” | 2-17 cm
1.6”-13.8” | 4-35 cm
Atolla Jellyfish
17.000
17.000
35.000
1200
3D
Atolla Jellyfish
12.6”-47” | 32-119 cm
15.75”-59” | 40-150 cm
29”-108” | 74-274 cm
55-88 lb | 25-40 kg
2-6 months
Barrel Jellyfish
119.000
150.000
274.000
40.000
0.50
6400
3D
Barrel Jellyfish
8.3”-18.9” | 21-48 cm
16”-36” | 40.6-91.4 cm
44”-104” | 112-264 cm
6-12 months
Black Sea Nettle Jellyfish
48.000
91.400
264.000
1.00
350
3D
Black Sea Nettle Jellyfish
.59”-6.3” | 1.5-16 cm
.47”-3.94” | 1.2-10 cm
.59”-6.3” | 1.5-16 cm
Bloodybelly Comb Jellyfish
16.000
10.000
16.000
100
3D
Bloodybelly Comb Jellyfish
27.6”-35.4” | 70-90 cm
31.5”-39.4” | 80-100 cm (Diameter)
31.5”-39.4” | 80-100 cm (Diameter)
Blue Coral
90.000
100.000
100.000
17400
3D
Blue Coral
7.1”-13.8” | 18-35 cm
9.84”-17.72” | 25-45 cm
24.8”-44.9” | 63-114 cm
1 year
Blue Jellyfish
35.000
45.000
114.000
1.00
5800
3D
Blue Jellyfish
9.8”-19.7” | 25-50 cm
11.8”-23.6” | 30-60 cm (Diameter)
11.8”-23.6” | 30-60 cm (Diameter)
Bubble Coral
50.000
60.000
60.000
5300
3D
Bubble Coral
5.5”-7.9” | 14-20 cm
7.1”-9.84” | 18-25 cm
7.5”-10.6” | 19-27 cm
.31-3 lb | .14-1.38 kg
3-6 months
Cannonball Jellyfish
20.000
25.000
27.000
1.380
0.50
12000
3D
Cannonball Jellyfish
3.5”-6.3” | 9-16 cm
5.9”-10” | 15-25.4 cm
16.5”-27.2” | 42-69 cm
.44-5.3 lb | .2-2.4 kg
1 year
Compass Jellyfish
16.000
25.400
69.000
2.400
1.00
5600
3D
Compass Jellyfish
8.7”-19.7” | 22-50 cm
9.84”-23.62” | 25-60 cm
13”-30.7” | 33-78 cm
.04-.89 lb | .02-.4 kg
3-6 months
Crowned Jellyfish
50.000
60.000
78.000
0.400
0.50
5
3D
Crowned Jellyfish
.5”-5.9” | 1.2-15 cm
.8”-10” | 2-25.4 cm
1.2”-14.2” | 3-36 cm
2-6 months
Crystal Jellyfish
15.000
25.400
36.000
0.50
1500
3D
Crystal Jellyfish
.3”-.63” | .8-1.6 cm
.39”-.79” | 1-2 cm
.67”-1.34” | 1.7-3.4 cm
Darth Vader Jellyfish
1.600
2.000
3.400
40
3D
Darth Vader Jellyfish
4’-8’ | 1.22-2.43 m
11.5’-13’ | 3.5-3.96 m (Diameter)
11.5’-13’ | 3.5-3.96 m (Diameter)
Elkhorn Coral
243.000
396.000
396.000
1450
3D
Elkhorn Coral
5.1”-6.3” | 13-16 cm
5.9”-7.9” | 15-20 cm (Diameter)
5.9”-7.9” | 15-20 cm (Diameter)
Finger Coral
16.000
20.000
20.000
1340
3D
Finger Coral
4.7”-5.9” | 12-15 cm
4.72”-5.91” | 12-15 cm
8.3”-10.6” | 21-27 cm
4-6 months
Flower Hat Jelly
15.000
15.000
27.000
0.50
150
3D
Flower Hat Jelly
1.6”-8.7” | 4-22 cm
2.36”-11.8” | 6-30 cm
2”-10.2” | 5-26 cm
4-6 months
Fried Egg Jellyfish
22.000
30.000
26.000
0.50
2000
3D
Fried Egg Jellyfish
10.2”-41.3” | 26-105 cm
15.75”-78.75” | 40-200 cm
28.3”-143” | 72-362 cm
200-480 lb | 91-217 kg
1 year
Lion’s Mane Jellyfish
105.000
200.000
362.000
217.000
1.00
6900
3D
Lion’s Mane Jellyfish
.79”-2.75” | 2-7 cm
1.18”-3.94” | 3-10 cm
3.15”-11” | 8-28 cm
6-9 months
Mauve Stinger
7.000
10.000
28.000
0.75
2300
3D
Mauve Stinger
3.94”-9.1” | 10-23 cm
5.91”-13.78” | 15-35 cm
7.1”-16.5” | 18-42 cm
.01-.07 lb | .01-.03 kg
8-12 months
Moon Jellyfish
23.000
35.000
42.000
0.030
1.00
56000
3D
Moon Jellyfish
7.9”-11.8” | 20-30 cm
11.8”-19.7” | 30-50 cm (Diameter)
11.8”-19.7” | 30-50 cm (Diameter)
Organ Pipe Coral
30.000
50.000
50.000
2400
3D
Organ Pipe Coral
22”-27.2” | 56-69 cm
30”-36” | 76.2-91.4 cm
55”-67” | 140-170 cm
30-50 lb | 14-23 kg
Pink Meanie Jellyfish
69.000
91.400
170.000
23.000
1200
3D
Pink Meanie Jellyfish
2”-5.1” | 5-13 cm
4.72”-11.8” | 12-30 cm
8.7”-23.2” | 22-59 cm
1 year
Portuguese Man o' War
13.000
30.000
59.000
1.00
17000
3D
Portuguese Man o' War
3.5”-5.1” | 9-13 cm
2.95”-3.94” | 7.5-10 cm
6.7”-9.1” | 17-23 cm
Red Paper Lantern Jellyfish
13.000
10.000
23.000
5
3D
Red Paper Lantern Jellyfish
3’-5’ | .91-1.52 m
3.3’- 9.8’ | 1-3 m (Diameter)
3.3’- 9.8’ | 1-3 m (Diameter)
Staghorn Coral
152.000
300.000
300.000
2500
3D
Staghorn Coral
13.4”-14.2” | 34-36 cm
17.7”-19.7” | 45-50 cm
36.2”-41.7” | 92-106 cm
20-24 lb | 9-11 kg
1 year
White-Spotted Jellyfish
36.000
50.000
106.000
11.000
1.00
410
3D
White-Spotted Jellyfish
White-Spotted Jellyfish (Phyllorhiza punctata)
Dimensioned comparison drawing of the White-spotted Jellyfish compared to other jellyfish and a person

The White-Spotted jellyfish, known scientifically as Phyllorhiza punctata, is a white bell shaped jelly with polka dots adorning its cap. The White-Spotted jellyfish is not a threat to humans as its sting and venom are very mild. The sting and venom of the White-Spotted jelly are so mild that it does not use its sting to hunt. Instead, the White-Spotted jellyfish filter feeds. Unfortunately, the White-Spotted jellyfish can filter feed in such massive quantities that it prevents other animals from being able to find food. This is problematic in areas where the White-Spotted jelly is an invasive species as these habitats do not have the jellyfish’s main predator to control its population. The White-Spotted jellyfish is native to the Pacific ocean between Australia and Japan.

White-spotted Jellyfish have a bell width between 17.7”-19.7” (45-50 cm), bell height of 13.4”-14.2” (34-36 cm), and overall length of 36.2”-41.7” (92-106 cm). The typical lifespan of the White-spotted Jellyfish is 1 year with a weight between 20-24 lb (9-11 kg).

Set of scaled elevation drawings of the White-spotted Jellyfish viewed from the front and side
The White-Spotted jellyfish, known scientifically as Phyllorhiza punctata, is a white bell shaped jelly with polka dots adorning its cap. The White-Spotted jellyfish is not a threat to humans as its sting and venom are very mild. The White-Spotted jellyfish is native to the Pacific ocean.

White-spotted Jellyfish have a bell width between 17.7”-19.7” (45-50 cm), bell height of 13.4”-14.2” (34-36 cm), and overall length of 36.2”-41.7” (92-106 cm). The typical lifespan of the White-spotted Jellyfish is 1 year with a weight between 20-24 lb (9-11 kg).

Set of scaled elevation drawings of the White-spotted Jellyfish viewed from the front and side
White-Spotted Jellyfish (Phyllorhiza punctata)
Height:
13.4”-14.2” | 34-36 cm
Width:
17.7”-19.7” | 45-50 cm
Length:
36.2”-41.7” | 92-106 cm
Depth:
Weight:
20-24 lb | 9-11 kg
Area:
Scientific Name
Phyllorhiza punctata
Lifespan
1 year

Drawings include:

White-spotted Jellyfish side elevation, front, top

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Pink Meanie Jellyfish (Drymonema larsoni)
Scale illustration of an average Pink Meanie Jellyfish with dimensions length compared to a human and jellyfish

The Pink Meanie, known scientifically as Drymonema larsoni, is one of the most rare jellyfish that is usually only found when blooms of jellyfish are abundant. The Pink Meanie feeds on other jellyfish, so it can usually be spotted within a pack of jellyfish ready for its feast. The Pink Meanie has been spotted on only a few occasions, so little is truly known about this species. The Pink Meanie has been spotted in Mexico, the Mediterreanean, and off the coast of South Africa. The Pink Meanie’s favorite snack is moon jellies and can consume up to 34 jellyfish at once by entangling them in its long tentacles and digesting them within hours.

Pink Meanie Jellyfish have a bell width between 30”-36” (76.2-91.4 cm), bell height of 22”-27.2” (56-69 cm), and overall length of 55”-67” (140-170 cm). The typical weight of the Pink Meanie Jellyfish is between 30-50 lb (14-23 kg).

Pair of elevation illustrations of the Pink Meanie Jellyfish seen from the side and front
The Pink Meanie, known scientifically as Drymonema larsoni, is one of the most rare jellyfish that is usually only found when blooms of jellyfish are abundant. The Pink Meanie feeds on other jellyfish, so it can usually be spotted within a pack of jellyfish ready for its feast.

Pink Meanie Jellyfish have a bell width between 30”-36” (76.2-91.4 cm), bell height of 22”-27.2” (56-69 cm), and overall length of 55”-67” (140-170 cm). The typical weight of the Pink Meanie Jellyfish is between 30-50 lb (14-23 kg).

Pair of elevation illustrations of the Pink Meanie Jellyfish seen from the side and front
Pink Meanie Jellyfish (Drymonema larsoni)
Height:
22”-27.2” | 56-69 cm
Width:
30”-36” | 76.2-91.4 cm
Length:
55”-67” | 140-170 cm
Depth:
Weight:
30-50 lb | 14-23 kg
Area:
Scientific Name
Drymonema larsoni
Lifespan

Drawings include:

Pink Meanie Jellyfish side elevation, front, top

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Portuguese Man o' War (Physalia physalis)
Dimensioned comparison drawing of the Portuguese Man o' War compared to other jellyfish and a person

The Portuguese Man O’ War, known scientifically as Physalia physalis, is often mistaken for a jellyfish, when in reality it is a siphonophore, a colonial organism made up of multiple smaller zooids. The Portuguese Man O’ War is considered to be the same species as the Pacific Man O’ War. The Portuguese Man O’ War consists of its top, called a pneumatophore, which is mainly translucent blue with hints of purple, that is filled with carbon monoxide and acts as a sail and flotation device for the organism. Dangling from its top are the Portuguese Man O’War’s killer tentacle zooids which kill fish, and have even killed humans, as it floats along the top of the ocean surface. The Portuguese Man O’ War lives solely on the ocean’s surface making it a member of the neuston, a highly complex ecology of ocean surface dwelling creatures, of which little is known.

Portuguese Man o' Wars have a bell width between 4.72”-11.8” (12-30 cm), bell height of 2”-5.1” (5-13 cm), and overall length of 8.7”-23.2” (22-59 cm). The typical lifespan of the Portuguese Man o' War is 1 year.

Set of scaled elevation drawings of the Portuguese Man o' War viewed from the front and side
The Portuguese Man O’ War, known scientifically as Physalia physalis, is often mistaken for a jellyfish, when in reality it is a siphonophore, a colonial organism made up of multiple smaller zooids. The Portuguese Man O’ War is considered to be the same species as the Pacific Man O’ War.

Portuguese Man o' Wars have a bell width between 4.72”-11.8” (12-30 cm), bell height of 2”-5.1” (5-13 cm), and overall length of 8.7”-23.2” (22-59 cm). The typical lifespan of the Portuguese Man o' War is 1 year.

Set of scaled elevation drawings of the Portuguese Man o' War viewed from the front and side
Portuguese Man o' War (Physalia physalis)
Height:
2”-5.1” | 5-13 cm
Width:
4.72”-11.8” | 12-30 cm
Length:
8.7”-23.2” | 22-59 cm
Depth:
Weight:
Area:
Scientific Name
Physalia physalis
Lifespan
1 year

Drawings include:

Portuguese Man o' War side elevation, front, top

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Bloodybelly Comb Jellyfish (Lampocteis cruentiventer)
Dimensioned comparison drawing of the Bloodybelly Comb Jellyfish compared to other jellyfish

The Bloodybelly Comb jellyfish, also known as Lampocteis cruentiventer, is a bioluminescent red jellyfish with a bloody red belly which most likely conceals it to predators. The Bloodybelly Comb jellyfish lives in the deep ocean in the oxygen minimum zone. Despite its bright red appearance, the Bloodybelly Comb actually blends into its surrounds as everything dark red that deep appears black. The Bloodybelly Comb is covered in tiny cilia which propel the jellyfish around. The Bloodybelly Comb is not yet on display in any aquariums in the United States and photos and videos have only been obtained through the use of remotely operated vehicles.

Bloodybelly Comb Jellyfish have a bell width between .47”-3.94” (1.2-10 cm), height of .59”-6.3” (1.5-16 cm), and overall length of .59”-6.3” (1.5-16 cm).

Set of scaled elevation drawings of the Bloodybelly Comb Jellyfish viewed from the front and side
The Bloodybelly Comb jellyfish, also known as Lampocteis cruentiventer, is a bioluminescent red jellyfish with a bloody red belly which most likely conceals it to predators. The Bloodybelly Comb jellyfish lives in the deep ocean in the oxygen minimum zone.

Bloodybelly Comb Jellyfish have a bell width between .47”-3.94” (1.2-10 cm), height of .59”-6.3” (1.5-16 cm), and overall length of .59”-6.3” (1.5-16 cm).

Set of scaled elevation drawings of the Bloodybelly Comb Jellyfish viewed from the front and side
Bloodybelly Comb Jellyfish (Lampocteis cruentiventer)
Height:
.59”-6.3” | 1.5-16 cm
Width:
.47”-3.94” | 1.2-10 cm
Length:
.59”-6.3” | 1.5-16 cm
Depth:
Weight:
Area:
Scientific Name
Lampocteis cruentiventer
Lifespan

Drawings include:

Bloodybelly Comb Jellyfish side elevation, front, top

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Red Paper Lantern Jellyfish (Pandea rubra)
Measured comparison illustration of the size of a Red Paper Lantern Jellyfish to other jellyfish

The Red Paper Lantern jellyfish, known scientifically as Pandea rubea, is not a true jellyfish, but rather a hydrozoan that resembles a jellyfish in appearance that lives in the deep ocean. The Red Paper Lantern jellyfish has a cap that resembles a red paper lantern that crinkles and extends in order to propel itself. The Red Paper Lantern is found in the cold, deep, dark ocean waters in the North Pacific, North Atlantic, and Southern Ocean in Japan. The Red Paper Lantern jellyfish provides a home to other deep sea critters, such as sea spiders, amphipods, and even other, smaller, jellyfish.

Red Paper Lantern Jellyfish have a bell width between 2.95”-3.94” (7.5-10 cm), bell height of 3.5”-5.1” (9-13 cm), and overall length of 6.7”-9.1” (17-23 cm).

Scaled collection of drawings of Red Paper Lantern Jellyfish in front and side poses
The Red Paper Lantern jellyfish, known scientifically as Pandea rubea, is not a true jellyfish, but rather a hydrozoan that resembles a jellyfish in appearance that lives in the deep ocean. The Red Paper Lantern jellyfish has a cap that resembles a red paper lantern that crinkles and extends.

Red Paper Lantern Jellyfish have a bell width between 2.95”-3.94” (7.5-10 cm), bell height of 3.5”-5.1” (9-13 cm), and overall length of 6.7”-9.1” (17-23 cm).

Scaled collection of drawings of Red Paper Lantern Jellyfish in front and side poses
Red Paper Lantern Jellyfish (Pandea rubra)
Height:
3.5”-5.1” | 9-13 cm
Width:
2.95”-3.94” | 7.5-10 cm
Length:
6.7”-9.1” | 17-23 cm
Depth:
Weight:
Area:
Scientific Name
Pandea rubra
Lifespan

Drawings include:

Red Paper Lantern Jellyfish side elevation, front, top

Details & Downloads

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