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Home › Ocean Species › Marine Animals › Vertebrates › Handfish

Interesting Facts about Handfishes

[Handfish Phylum: Chordata] [Class: Actinopterygii] [Order: Lophiiformes] [Family: Brachionichthyidae]

Noted for its highly modified pectoral fins, Brachionichthyidae is a clambering anglerfish species that uses "hands" to walk about on the sea floor instead of swimming.

This guide contains some extraordinary and unique facts about handfishes (suborder Antennarioidei), particularly where they still exist today, what they eat, and how they reproduce.

Handfish Geographical Range and Habitats

Only a handful of handfish remain in existence, and they all live in the temperate coastal waters of southeastern Australia.

In particular, the best place to find these small, bottom-dwelling fish is Tasmania (and some parts of Victoria).

Handfishes tend to inhabit the shallow, sunlit zones (neritic) of marine and brackish environments.

Most of the handfish species exist in depths ranging between one (1) and sixty (60) metres. But, there have been sightings at 200 metres below sea level.

They are ray-finned marine vertebrates that prefer seafloor habitats. Even though genus Brachionichthys thrives better around sand and muddy substrates, they can also tolerate sponge gardens and seagrass beds - especially when they start spawning.

Handfish Behaviour and Characteristics

Similar to hawkfishes, one of the notable features of handfish is their pectoral fins, which show some resemblance to human hands.

The modifications provide them with a means to crawl or "walk" along the seafloor - even though the movement is slow and rather clumsy looking.

Other distinguishing features of handfishes are the girthy head, flattened body shape, and skin covered in wartlike protuberances and dermal denticles (tooth-like scales).

Moving on...

The vibrant hues of some species (e.g., the red handfish) are remarkable for a fish that lives in water bodies prone to mercury contamination and the discharge of urban effluent.

By comparison, the body of the spotted handfish (Brachionichthys hirsutus) is a colourful kaleidoscope of marbled spots and disorderly patterns.

There are about fourteen surviving handfish species and all of them are small, mostly between five (5) and fifteen (15) centimetres long (2 to 6 inches).

Thymichthys politus is considered as one of the smallest handfish, rarely growing more than six centimetres long.

Whereas, fully grown Brachiosaurus ziebelli is one of the biggest handfish, often reaching a total length of fifteen centimetres.

Interesting Fact: Even though handfishes possess a version of an anglerfish's illicium (the modified dorsal fin ray protruding above the mouth), it is quite short and appears to be less successful as a fishing lure than those seen in predacious anglerfishes of the order Lophiiformes.

What Do Handfishes Eat?

In fact, handfish are carnivorous creatures so they predominantly consume small benthic invertebrates and similar bottom-dwelling crustaceans.

For the most part, the daily diet for handfishes will include:

• Amphipods
• Copepods
• Polychaete worms
• Sea snails
• Shrimp
• Small marine insects
• Soft-bodied mollusks

Using the hand-like pectoral fins for movement, these ambush predators rely on vulnerable prey for a food source.

But, being relatively small and having limited scope for mobility, generally means they feed on organisms that are easily accessible in the vicinity of their surroundings.

Interesting Fact: The primary reason they stay close to the sea floor and clamber about - rather than swimming around and hunting with controlled buoyancy like most fishes - is that handfish do not have a swim bladder.

Types of Handfish Species

How Do Handfish Reproduce?

The reproductive traits of handfish are similar to most oviparous fish. The female lays a small clutch of eggs, more than twenty and up to one hundred, and then she guards them.

She attaches the sticky egg mass to a suitable structure, such as a sea sponge or a strong clump of seagrass, until the larvae hatch as fully formed juvenile handfishes. Thus, they skip the free-swimming planktonic phase.

In case you're wondering...

Even though parental care is not common in many vertebrate fishes, this is not the case in handfish. They actually exhibit strong guardianship to help ensure proper and safe development of the young.

Although definitive and accurate documentation is sparse, scientists believe the warmth of summertime in Australia provides the trigger for the breeding season.

Threats and Predators

There are several key reasons why successful reproduction in handfishes is vital for their long term survival. One is their relatively small clutch size, which culminates in a low reproductive output.

As a direct consequence, the population status of almost all species of handfishes is threatened. For instance, both the red handfish and spotted handfish are classed as critically endangered.

Other noteworthy factors that also contribute to their demise include:

• Loss of habitat (mainly due to coastal development)
• Decline in seagrass beds (due to issues with water quality)
• Invasive marine species (e.g. the northern Pacific seastar)
• Rising sea temperatures (including ocean acidification)
• Severe storms and changing currents (creating unstable water temperatures)
• Underwater pollution (caused by runoff from agriculture).

Furthermore, the natural predators of these slow-moving, bottom-dwellers are also causing a significant decline in their survival rates.

Typical examples include scorpionfishes, crab species, and flatheads, especially the dusky flathead (Platycephalus fuscus).

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