“…And today we’re telling about a creature that sounds likes a bad thing to call someone.”
Beneath the briny blue of South Africa’s coastal waters lurks a creature with a schnoz so prominent it could co-star with the proboscis monkey in a muppet movie. The black musselcracker, a reef-roaming, shell-smashing singleton, chomps through crustaceans like a kid through Halloween candy. With a face that only a mother could love, this fish hides a secret that flips its life story like a dramatic soap opera plot twist. But sometimes it pays to be a deep-sea drama queen, it’s the black musselcracker here in Life, Death, and Taxonomy.
Description
Physical Characteristics:
- Distinctive large, fleshy “nose” and robust jaws, with a head considered a delicacy in some regions.
- Dorsal spines: 12; dorsal soft rays: 10; anal spines: 3; anal soft rays: 8.
Measure Up
Length of Black Musselcracker
Cymatoceps nasutus has a total length of 150 cm (59 inches). How many fish, laid end to end, fit into the length of these South Africa-related objects?
Question: How many fit into each length comparison?
A) 1.8 Cymatoceps nasutus go into the length of a Zulu iklwa spear
B) 1.3 Cymatoceps nasutus go into the length of a Cape fur seal
C) 4.2 Xhosa clay pots go into the length of a Cymatoceps nasutus
a) The length of a Zulu iklwa spear
The iklwa, a Zulu warrior’s short stabbing spear, measures about 150 cm (1.5 meters or 59 inches).
b) The length of a Cape fur seal
The Cape fur seal (Arctocephalus pusillus pusillus) reaches about 200 cm (2 meters or 78.7 inches) for a large male.
c) The diameter of a Xhosa clay pot
A Xhosa clay pot (imbiza) has a diameter of about 45 cm (0.45 meters or 17.7 inches), shorter than the fish.
Weight of Black Musselcracker
Cymatoceps nasutus weighs 34.4 kg (75.8 pounds). How many fish fit into the weight of these South Africa-related objects?
Question: How many fit into each weight comparison?
A) 7.2 rock hyraxes go into the weight of a Cymatoceps nasutus
B) 6.9 Ndebele beaded aprons go into the weight of a Cymatoceps nasutus
C) 1.8 Cymatoceps nasutus goes into the weight of a great white shark pup
a) The weight of a rock hyrax
The rock hyrax (Procavia capensis) weighs about 4 kg (8.8 pounds), lighter than the fish.
b) The weight of a Ndebele beaded apron
A Ndebele beaded apron (isiphephetu) weighs about 5 kg (11 pounds), lighter than the fish.
c) The weight of a great white shark pup
A great white shark pup (Carcharodon carcharias) weighs about 34 kg (74.8 pounds), nearly equal to the fish.
Fast Facts
Habitat and Distribution:
- Endemic to South Africa, found from Maputo (Mozambique) to Cape Town, along the Western Indian Ocean (22°S–35°S).
- Inhabits shallow, rocky coastal areas and offshore reefs to a depth of 80 m, rarely entering estuaries.
Diet: Feeds on hard-shelled invertebrates like crabs, crayfish, and sea urchins, using strong jaws to crush prey.
Life History:
- Protogynous hermaphrodite (starts as female, may change to male).
- Slow-growing, long-lived, with a generation length of ~16 years.
- Reaches maturity around 53 cm.
Behavior:
- Highly resident, with 84.6% of tagged individuals recaptured within 1 km of tagging sites, though some move up to 528 km.
- Aggressive apex predator, making it vulnerable to fishing due to its willingness to take almost any bait.
Major Fact: A Man for Some Seasons
- Black musselcrackers are protogynous sequential hermaphrodites, starting life as females and transitioning to males later in life.
- This sex change typically occurs around 18 years of age or when they reach about 70 cm (27.5 in) in length.
- The transition is triggered by social and environmental cues, like the absence of dominant males in the population.
- This is thought to be the result of the stress hormone cortisol triggering a change in the amounts of estradiol and ketotestosterone, causing their hardware to change along with their software over time.
- As females, they mature at around 10 years and 53 cm fork length, laying eggs near reefs during winter spawning (May to October).
- Changing to male allows them to take on dominant roles, defending territories and mating with multiple females.
- This strategy maximizes reproductive success, as larger males can monopolize mating opportunities in polygynous systems.
- Overfishing of large males can skew sex ratios, potentially causing females to transition earlier or at smaller sizes.
- The process ensures species survival by maintaining a balance of males and females, even in low-male populations.
- Their slow growth and long lifespan (up to 45.5 years) make this late-life switch a high-stakes gamble.
- Protogyny is common in reef fish like wrasses and sparids, but the musselcracker’s solitary nature makes its transition a lonely journey.
Ending
So crack open a few mussels, read the room, then transition to the most socially profitable gender like the black musselcracker here in LDT.