Dive Dry with Dr. Bill

#357: Up a Tree... Fish!

The beautiful kelp beds off Catalina and southern California are often referred to as kelp forests because the vertical structure of the large seaweeds resembles that of trees. Of course algae and trees are not closely related despite the fact that both create great habitat for other living critters, conduct photosynthesis to produce oxygen, and provide food for other life forms. But I'm not going to write about forests today. Instead, my focus is on a member of the scorpionfish family... the questionably named treefish (Sebastes serriceps). I have yet to uncover the reason why this fish was given its name.

Since there are no trees in our kelp forests, I have yet to understand why a fish would receive such a name. I have never seen it up a giant kelp much less a tree. It is a resident of our rocky reefs, often seen resting on the rocks or in crevices like other members of the scorpionfish family... which includes rockfish and scorpionfish. In fact, I don't think I've ever seen a treefish doing much of anything other than that, whether I observe them during day or night. They just sit there, all by their lonesome. Not a life I could be happy with, although I am seen occasionally just sitting on the wall watching the people go by (well, watching about half of them anyway).

Treefish reach a maximum length of about 16 inches but are most commonly in the 10 to 12 inch range. They are one of the easiest of our local fish to identify... right up there with the garibaldi. Theis species has a bright to dull yellow background with dark gray to solid black vertical stripes. Like other members of their family, they have sharp spines. In fact, the species name serriceps means "saw head." Another very distinctive feature of the adult fish is their pink lips. They look like young teenage girls who have tried applying lipstick for the first time. I grew up with three younger sisters so I know something about this! Despite their lip gloss, these fish are almost always solitary... although they must "get together" some time to create their beautiful young 'uns.

Treefish are found from San Francisco to central Baja California in the region of Cedros Island. They are most common south of Point Conception. Their normal depth range is reported by Dr. Milton Love as 20 to 140 feet. Although secretive, they are commonly seen in the Casino Point Dive Park if a diver looks closely in all the nooks and crannies.

Years ago I was told that these fish must be night or nocturnal feeders since all they do is sit still during the day. I've been doing a number of night dives this year and all I've seen them do at night is sit as well. Dr. Love suggests they may be dawn and dusk predators, although I've yet to see any munching by them in the early evening. Obviously they have to eat some time. Their prey is believed to consist of benthic or bottom-dwelling invertebrates like shrimp and crabs as well as small fish. Treefish are believed to be ambush predators which means they can jump out and grab poor unsuspecting prey as it drifts past their resting place. Obviously I'm not there at the exact time they lunge. Perhaps after a few billion night dives, I'll get to film their feeding behavior.

A major reason why treefish are observed solo underwater is the fact that they are very territorial. Although not as aggressive as our garibaldi in defending their territories, treefish will "greet" an intruder of the same species by flaring their mouths. Dr. Love believes their pink to reddish lips may be involved in this territorial display and be used to warn other treefish off. I know that women who wear lipstick often drive me away... but then so do the ones who don't. Sigh.

Adult treefish tend to be dull in coloration. The yellow body is a bit "dirtier" and the dark bands are more charcoal than black. The true stars of this species are the young treefish that are also frequently seen in the dive park during summer. Their body color is a bright yellow and the bars are usually a solid black, making them stunning subjects for cameras. Another difference between the young and the adult is that the little ones are almost frenetic in their swimming behavior. I rarely see them sit still like their mommies and daddies. Instead they seem in constant motion with fins working overtime... kind of like two year old humans! At least they don't whine... at least as far as my ears can tell.

Treefish are sexually mature beginning at about three years in males and four in females. They are viviparous which means that they give live birth to their young, rather than laying eggs in a nest or casting them off into the plankton. In live bearers, the young may be in larval stage or miniatures of the adults. Based on my research, the young of treefish are born in larval form and drift in the plankton for about three months. Dr. Love states that they are found offshore associated with drifting kelp rafts or paddies which indicates they may transition to juveniles within the plankton before settling to the bottom during summer. This would enable them to disperse to new habitat, thus allowing for colonization of new areas and the enhancement of the gene pools at already inhabited sites. Personally, my mixing of genes is most likely at an end. In fact, I've considered creating a t-shirt that reads "It is illegal for any woman to copy even a portion of my DNA." Of course I have to cooperate in that.

© 2009 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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The sluggish, sedentary adults with a close up of their lips and the frisky juvenile treefish
with one hiding beneath the protective spines of a sea urchin.

This document maintained by Dr. Bill Bushing.
Material and images © 2009 Star Thrower Educational Multimedia