Ophiarachna incrassata, widely known as the Green Brittle Star or Thick-armed Brittle Star, is a large, predatory marine echinoderm native to the Indo-West Pacific. Highly active and robust, it is famous among aquarists for its striking appearance and surprising predatory behavior.
Physical Characteristics
Size: It is one of the largest brittle stars, with a central disc (body) that can measure up to \(5\) cm (\(2\) inches) in diameter. Its five arms can grow up to \(20\) to \(25\) cm (\(8\) to \(10\) inches) long, giving the entire creature a striking span of up to \(50\) cm (\(20\) inches).
Coloration: Its base color ranges from muted or bright green to brownish-green. The central disc is typically adorned with lighter yellowish dots or markings, and the arms are often lined with alternating whitish to yellowish-white spines.
Habitat and Range
Natural Range: Widespread throughout the tropical Indo-West Pacific, spanning from the Red Sea to Hawaii and the coasts of northern Australia and Japan.
Environment: Found in shallow, tropical littoral waters, usually at depths of less than \(10\) meters (\(30\) feet). They are benthic dwellers, commonly found on reef flats tucked among coral rubble, rocks, seagrass beds, and algae.
Diet and Behavior
Feeding Habits: Unlike many brittle stars that strictly scavenge, Ophiarachna incrassata is a highly capable predator. While they will eat detritus, zooplankton, and meaty leftovers, they also actively hunt and capture small fish and other invertebrates using their thick, flexible arms.
Movement: They use their arms to crawl rapidly across the seafloor, making them surprisingly fast for echinoderms.
Temperament: They are solitary and generally secretive, often hiding in rock crevices during the day. They are known to be somewhat aggressive toward other tank inhabitants and should be kept with caution in reef aquariums containing small, sleeping fish
Ophiomastix is a genus of brittle stars characterized by five long, slender arms featuring distinct, paddle-shaped or club-like spines. Often found in Indo-Pacific shallow coral reefs, they are typically colorful (red, brown, black, or tan) and act as nocturnal scavengers and detritivores, hiding in crevices during the day.
Key Characteristics
Arm Spines: The defining feature is the presence of club-like, enlarged, or paddle-shaped arm spines.
Appearance: They have a small, distinct central disk (roughly 2–3 cm) and long arms (up to 20 cm or more).
Coloration: Colors vary widely, including shades of red, brown, tan, or white, often with patterned lines.
Species Examples:
Ophiomastix annulosa (Knobby Fancy Brittle Star): Known for "chain-link" patterns, reddish-brown colors, and 5 long arms with blunt spines.
Ophiomastix venosa: Found in the Indo-Pacific, featuring a golden or brown disk with club-like spines.
Ophiomastix variabilis: Displays five slender arms with club-shaped spines.
Behavior and Habitat
Habitat: Commonly found in subtidal zones, underneath coral rubble, in rock crevices, or on sandy bottoms in tropical reefs.
Diet: They are primarily nocturnal scavengers and detritivores, feeding on decaying organic matter, algae, and small debris.
Reproduction: These starfish can spawn throughout the year, with female stars producing planktonic larvae.
Defense: They are known to possess modified spines, and some species may be toxic or use slime, though they are generally considered reef-safe in aquariums.
Aquarium Care
Hardiness: Considered to have moderate care requirements, but they are sensitive to changes in salinity/specific gravity.
Tank Setup: Require a minimum of 100 gallons, with plenty of live rock for hiding.
Compatibility: Generally peaceful but can be opportunistic feeders if underfed.
The Purple Linckia Starfish (Linckia sp., often L. laevigata color morph or Leiaster teres) is a striking echinoderm known for its deep purple coloration, long, slender, cylindrical arms with rounded tips, and sometimes a "fuzzy" or smooth, firm texture. These sea stars are popular in the marine aquarium hobby for their vibrant color and peaceful nature, though they are considered expert-only due to specialized feeding requirements.
Description and Characteristics
Coloration: Ranges from deep purple to lavender, often with a velvety, "fuzzy" appearance.
Size: Can grow up to 30 cm (11.8 in) in diameter, with aquarium specimens often seen around 8 inches.
Arms: Five long, cylindrical arms that are slightly tapered, often appearing like "Play-Doh" models.
Tube Feet: Possesses short, bright yellow tube feet used for movement, which contrasts with the purple body.
Regeneration: Possesses remarkable regenerative capabilities, able to regenerate a whole new star from a single severed arm.
Habitat and Behavior
Range: Found throughout the tropical Indo-Pacific region, inhabiting coral reefs and seagrass beds at depths of 6 to 85 meters.
Diet: Primarily a detritivore and scavenger, feeding on bacterial films, sponges, and microorganisms on rocks.
Activity: Generally active during the day, moving slowly across rocks and sand.
Aquarium Care Requirements
Acclimation: Requires a very slow, long drip acclimation (at least 2.5 to 4 hours) to adjust to new water parameters.
Tank Size: Requires large, well-established aquariums (usually 55-100+ gallons) with ample live rock to support their feeding needs.
Sensitivity: Very intolerant of sudden changes in salinity, pH, and oxygen levels. They are highly sensitive to copper-based medications.
Diet in Captivity: Feeds on established bacteria films and microfauna in the tank; they are difficult to target-feed, making a mature tank essential.
Ophiolepis superba, also known as the banded brittle star or spotted snake starfish, is a marine invertebrate characterized by its distinctive color pattern and relatively short arms. It typically has a beige to pale yellow-orange base color with a striking pattern of black or purple on the disc and bands on the arms. The arms are smooth due to tiny spines, and the disc is covered with larger plates surrounded by a single row of smaller plates.
Key Features:
Size:
Disc diameter can reach up to 3 cm, with arm lengths up to 9 cm. Some sources indicate a total size of up to 25 cm.
Coloration:
Beige to pale yellow-orange with a pattern of black or purple on the disc and bands on the arms.
Arm Structure:
Short, relatively smooth arms due to small lateral spines.
Habitat:
Found in lower littoral zones and deeper waters, often under rocks and among coral, including coastal and deeper reef areas.
Distribution:
Indo-West Pacific region, including the Red Sea, East Indies, Australia, and the South Pacific Islands.
Behavior:
Solitary and spends much of its time hidden, particularly during the day, among rocks and corals. It is an omnivore with carnivorous tendencies, feeding on detritus and carrion.
Archaster typicus, commonly known as the sand sifting starfish or common sea star, is a marine invertebrate with a flat, gray or brownish body. They have five long, slightly tapering arms, though variations with three, four, or even six arms can occur. These starfish are adapted to life on sandy seabeds, where they bury themselves during high tide and move on the surface during low tide.
Key Characteristics:
Shape and Size: Five-limbed star with long, slightly tapering arms. Adults reach 12-15 cm in diameter.
Coloration: Grey or brownish, often with darker and lighter patches, sometimes forming a chevron pattern. Underside is pale.
Habitat: Sandy seabed, where they burrow and move over the surface.
Feeding: They are detritivores, feeding on organic matter in the sand.
Behavior: Active in the top layers of the sand, stirring it to prevent sediment buildup and promote oxygenation.
In Marine Aquariums:
Beneficial: They are popular in reef aquariums for cleaning and aerating the sand bed.
Peaceful and Reef-Safe: They are peaceful and won't harm fish, corals, or other invertebrates.
Maintenance: Require a thick sandy bottom and proper water conditions (temperature, pH).
Deep Cleaning: They stir the top layers of sand (up to 3 cm deep) but don't clean deeply below that.
Echinaster sepositus, the Mediterranean red sea star, is a species of starfish from the East Atlantic, including the Mediterranean Sea.
Description
Echinaster sepositus has five relatively slender arms around a small central disc. It usually has a diameter of up to 20 cm (8 in), but can exceptionally reach up to 30 cm (12 in).It is a bright orange-red in colour, and has a soapy surface texture unlike superficially similar Henricia starfish (another somewhat similar species from the same region is Ophidiaster ophidianus). The surface is dotted with evenly spaced pits from which the animal can extend its deep red gills (papula).
Distribution
Echinaster sepositus is found in the East Atlantic north of the Equator, including the Mediterranean Sea where it is one of the most common starfish (although virtually absent from some localities). Its northern limit is the English Channel, but only on the French side. It is found at depths of 1 to 250 m (3–820 ft) in a wide range of habitats, including rocky, sandy and muddy bottoms, and sea grass meadows (Posidonia oceanica and Zostera)
Most commonly found is pure blue, dark blue, or light blue, although observers find the aqua, purple, or orange variation throughout the ocean. These sea stars may grow up to 30 cm (11.8 in) in diameter, with rounded tips at each of the arms; some individuals may bear lighter or darker spots along each of their arms. Individual specimens are typically firm in texture, possessing the slightly tubular, elongated arms common to most of other members of the family Ophidiasteridae, and usually possessing short, yellowish tube feet. An inhabitant of coral reefs and sea grass beds, this species is relatively common and is typically found in sparse density throughout its range. Blue stars live subtidally, or sometimes intertidally, on fine (sand) or hard substrata and move relatively slowly (mean locomotion rate of 8.1 cm/min).
The genus Linckia, as is true of other species of starfish, is recognized by scientists as being possessed of remarkable regenerative capabilities, and endowed with powers of defensive autotomy against predators.Although not yet documented, L. laevigata may be able to reproduce asexually. L. laevigata is apparently not an exception to this behavior, as many individuals observed in nature are missing arms or, on occasion, in the comet form.
This sea star is fairly popular with marine aquarium hobbyists, where it requires a proper, slow acclimatization before entering the tank system, and an adequate food source similar to that found in its natural habitat. Generally thought of as a detritivore, many sources maintain that this species will indefinitely graze throughout the aquarium for organic films or sedentary, low-growing organisms such as sponges and algae. In the marine aquarium hobby, they have been seen to consume Asterina Starfish, which are commonly introduced into such aquaria on the ubiquitous "live rock" used in such settings.
Nardoa novaecaledoniae, also known as the Goldtip Starfish, Yellow Mesh Sea Star, or Peach Tip Mesh Sea Star, is a species of sea star in the family Ophidiasteridae. These starfish are found in the Indo-Pacific region, including areas like Australia, Indonesia, and the Philippines.
Key features of Nardoa novaecaledoniae:
Appearance: They are characterized by their vibrant coloration, often with a tan to brown body and golden or peach-colored tips on their arms. The arms can also have white spots on the central disc that get smaller as they move towards the arm tips.
Size: Nardoa novaecaledoniae can grow up to 10 inches (25 cm) in diameter.
Habitat: They typically inhabit shallow, rocky reefs.
Diet: They are omnivores, feeding on algae, small fish, and mussel flesh.
Care: They are not commonly seen in the home aquarium trade and can be sensitive to sudden changes in salinity.
Range: They are found in the Western Pacific Ocean.
