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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
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
GUIDE
3D
White-Spotted Jellyfish
Elkhorn Coral (Acropora palmata)
Dimensioned comparison drawing of the Elkhorn Coral compared to other corals and a person

The Elkhorn Coral (Acropora palmata) is a fast-growing coral easily identified by its complex branching structure composed of colonies of dense stands forming interlocking thickets. This structure makes it resemble elk antlers. It is mostly found in the Caribbean and Bahamas very close to the shoreline. As a result, it is under immense damage from human pollution and coral bleaching. The Elkhorn coral has a large body, and branches are sturdy and thick, which can be yellow to yellow-brown with white tips. This coral can reproduce sexually or asexually. It is considered a hard coral.

The Elkhorn Coral has an overall colony diameter between 11.5’-13’ (3.5-3.96 m) and typical height of 4’-8’ (1.22-2.43 m).

Set of scaled top and side view drawings of the Elkhorn Coral with dimensions
The Elkhorn Coral (Acropora palmata) is a fast-growing coral easily identified by its complex branching structure composed of colonies of dense stands forming interlocking thickets. This structure makes it resemble elk antlers. It is mostly found in the Caribbean and Bahamas very close to the shore.

The Elkhorn Coral has an overall colony diameter between 11.5’-13’ (3.5-3.96 m) and typical height of 4’-8’ (1.22-2.43 m).

Set of scaled top and side view drawings of the Elkhorn Coral with dimensions
Elkhorn Coral (Acropora palmata)
Height:
4’-8’ | 1.22-2.43 m
Width:
11.5’-13’ | 3.5-3.96 m (Diameter)
Length:
Depth:
11.5’-13’ | 3.5-3.96 m (Diameter)
Weight:
Area:
Scientific Name
Acropora palmata
Lifespan

Drawings include:

Elkhorn Coral top view, side (assorted)

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Atolla Jellyfish (Atolla wyvillei)
Dimensioned comparison drawing of the Atolla Jellyfish compared to other jellyfish and a person

The Atolla jellyfish, also known as Atolla wyvelli, is a deep-sea bioluminescent jellyfish. The Atolla jellyfish is a crown jellyfish and has about 20 tentacles of all equal length and then one longer tentacle it uses to capture prey. The Atolla jellyfish is named after Sir Charles Wyville Thomson, the lead scientist on the Challenger expedition. The Atolla jellyfish is also called the “alarm jellyfish” as it flashes its bioluminescent red when it is under attack in order to draw bigger predators to attack the creature it is under attack from. This “alarm” action has been mimicked by scientists in order to attract other deep sea creatures so they could be observed, such as the giant squid.

Atolla Jellyfish have a bell width between .79”-6.7” (2-17 cm), bell height of .79”-6.7” (2-17 cm), and overall length of 1.6”-13.8” (4-35 cm).

Set of scaled elevation drawings of the Atolla Jellyfish viewed from the front and side
The Atolla jellyfish, also known as Atolla wyvelli, is a deep-sea bioluminescent jellyfish. The Atolla jellyfish is a crown jellyfish and has about 20 tentacles of all equal length and then one longer tentacle it uses to capture prey. The Atolla jellyfish is named after Sir Charles Wyville Thomson.

Atolla Jellyfish have a bell width between .79”-6.7” (2-17 cm), bell height of .79”-6.7” (2-17 cm), and overall length of 1.6”-13.8” (4-35 cm).

Set of scaled elevation drawings of the Atolla Jellyfish viewed from the front and side
Atolla Jellyfish (Atolla wyvillei)
Height:
.79”-6.7” | 2-17 cm
Width:
.79”-6.7” | 2-17 cm
Length:
1.6”-13.8” | 4-35 cm
Depth:
Weight:
Area:
Scientific Name
Atolla wyvillei
Lifespan

Drawings include:

Atolla Jellyfish side elevation, front, top

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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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Darth Vader Jellyfish (Bathykorus bouilloni)
Dimensioned comparison drawing of the Darth Vader Jellyfish compared to other jellyfish

The Darth Vader jellyfish, known scientifically as Bathykorus bouilloni, despite being affectionately nicknamed Darth Vader jellyfish, is actually a hydrozoan found in the deep sea in the Arctic. The Darth Vader jellyfish is a very small, transparent light blue organism that lives at depths more than 3,300 feet below sea level. The Darth Vader jellyfish has a helmet shaped cap, thus giving it its moniker, with four long tentacles protruding from the top of the cap and four, short, secondary tentacles extending from the bottom. Due to the depths at which this creature lives, the Darth Vader jellyfish has yet to be observed with the human eye and is monitored only by remote operated vehicles.

Darth Vader Jellyfish have a bell width between .39”-.79” (1-2 cm), bell height of .3”-.63” (.8-1.6 cm), and overall length of .67”-1.34” (1.7-3.4 cm).

Set of scaled elevation drawings of the Darth Vader Jellyfish viewed from the front and side
The Darth Vader jellyfish, known scientifically as Bathykorus bouilloni, despite being affectionately nicknamed Darth Vader jellyfish, is actually a hydrozoan found in the deep sea in the Arctic. The Darth Vader jellyfish is a very small, transparent light blue organism with a helmet shape.

Darth Vader Jellyfish have a bell width between .39”-.79” (1-2 cm), bell height of .3”-.63” (.8-1.6 cm), and overall length of .67”-1.34” (1.7-3.4 cm).

Set of scaled elevation drawings of the Darth Vader Jellyfish viewed from the front and side
Darth Vader Jellyfish (Bathykorus bouilloni)
Height:
.3”-.63” | .8-1.6 cm
Width:
.39”-.79” | 1-2 cm
Length:
.67”-1.34” | 1.7-3.4 cm
Depth:
Weight:
Area:
Scientific Name
Bathykorus bouilloni
Lifespan

Drawings include:

Darth Vader Jellyfish side elevation, front, top

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Compass Jellyfish (Chrysaora hysoscella)
Scale illustration of an average Compass Jellyfish with dimensions length compared to a human and jellyfish

The Compass jellyfish, known scientifically as Chrysaora hysoscella, is a yellow-white jellyfish with brown markings on the top of its bell. These markings are v-shaped and radiant out from the center and resemble a compass, the Compass jellyfish’s namesake. Along the edge of the bell, the Compass jellyfish protrudes fringe with wavy oral arms and has tentacles hanging from the center of the bell. The Compass jelly has a powerful sting and should be avoided if recognized on the beach. The Compass jelly is common off the coast of Britain during the warmer summer months.

Compass Jellyfish have a bell width between 5.9”-10” (15-25.4 cm), bell height of 3.5”-6.3” (9-16 cm), and overall length of 16.5”-27.2” (42-69 cm). The typical lifespan of the Compass Jellyfish is 1 year with a weight between .44-5.3 lb (.2-2.4 kg).

Pair of elevation illustrations of the Compass Jellyfish seen from the side and front
The Compass jellyfish, known scientifically as Chrysaora hysoscella, is a yellow-white jellyfish with brown markings on the top of its bell. These markings are v-shaped and radiant out from the center and resemble a compass, the Compass jellyfish’s namesake.

Compass Jellyfish have a bell width between 5.9”-10” (15-25.4 cm), bell height of 3.5”-6.3” (9-16 cm), and overall length of 16.5”-27.2” (42-69 cm). The typical lifespan of the Compass Jellyfish is 1 year with a weight between .44-5.3 lb (.2-2.4 kg).

Pair of elevation illustrations of the Compass Jellyfish seen from the side and front
Compass Jellyfish (Chrysaora hysoscella)
Height:
3.5”-6.3” | 9-16 cm
Width:
5.9”-10” | 15-25.4 cm
Length:
16.5”-27.2” | 42-69 cm
Depth:
Weight:
.44-5.3 lb | .2-2.4 kg
Area:
Scientific Name
Chrysaora hysoscella
Lifespan
1 year

Drawings include:

Compass Jellyfish side elevation, front, top

Details & Downloads

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