Branchiostoma a.k.a. amphioxus a.k.a. lancelet in Southern California?

[Frank O]

Hi all, recently I've been reading a 1940 book on vertebrate biology that includes an interesting discussion of the Cephalochordata -- a small branch of the animal kingdom, the most widely known genus being Branchiostoma, or amphioxus, also known commonly as a lancelet. They caught my eye because they barely qualify as vertebrates, but only in a very primitive way.

Does anyone know if these are commonly seen on dives in Southern California? Lots of hits on google, but I haven't run across a lot so far to pin this down.

 

[LeslieH]

Hi Frank -- They're around but not commonly seen. You really have to go looking for them. Usually I see them when I'm sampling right off the beach & moving sand around. They dart in & out of the sand very quickly.

 

[Frank O]

Hi Leslie, nice to see you here! Someone else mentioned Ricketts' "Between Pacific Tides," which described their range as including Newport Harbor (convenient to me). However, I can't work up too much enthusiasm for turning over spadefuls of sand in search of them. Are they ever seen much out in the open? Or if they're burrowed, is there a distinctive look to their tentacles to be looking for? It sounds from Ricketts as though they're fairly small (overall length maximum 7 cm, most of them half that).

 

[LeslieH]

The only time I've seen them in the open was during very low tides when they were darting in & out chasing food particles at the lower edge of the surf zone as the sand was stirred up by waves. They've very fast, whitish or translucent (= hard to see) & really do just dive straight into the sand & out again - common names are sand lance and sand diver. They don't have permanent burrows. Newport Harbor has undergone tremendous alteration since "Between Pacific Tides" was first written. A lot of animals recorded from that area & also Dana Point are no longer to be found there.

 

[archman]

Lancelets are negatively phototactic... they don't like light. Try diving at night.

They're also interstitial detritivores... stick your head into the sand.