Intrasexual variations in arm morphology related to alternative reproductive tactics in Japanese spear squid

The morphology of organisms is closely connected to their ecological features and is adapted to their environments. Arms and tentacles, appendages of cephalopods, exhibit great morphological variations both among and within species based on their ecology, but its intrasexual variations remain unexplored. Males of the Japanese spear squid, Heterololigo bleekeri, in different size categories pursue alternative reproductive tactics (ARTs). Large ‘consort’ males copulate with females in a male-parallel position, while small ‘sneaker’ males copulate with females in a head-to-head position. These ARTs result in differences in mating position and hunting strategy based on body size, leading to a hypothesis that ARTs in H. bleekeri may be related to intrasexual variations in arm morphology. This hypothesis was tested by analyzing stomach contents, arm length, and the number of suckers on each arm with squid collected off Miyagi, Japan, during two spawning seasons from December to May in 2021–20..., , , # Intrasexual variations in arm morphology related to alternative reproductive tactics in Japanese spear squid

[https://doi.org/10.5061/dryad.0000000c7](https://doi.org/10.5061/dryad.0000000c7)

## Description of the data and file structure

Arms and tentacle length, the number of suckers on each arm, and stomach contents were analyzed for consort males, sneaker males, immature males, mature females, and immature females of the Japanese spear squid, *Heterololigo bleekeri* caught throughout the reproductive season. Sneaker males have longer arm I–IV compared to the other group.

The dataset (csv) contains sample ID, Mantle length, Reproductive status, Stomach contents, Catch date, Fishing Gear, Freezing/Thawing process, right Arm I–IV length, left Arm IV length, and Number of suckers on the right Arm I–IV of spear squid *Heterololigo bleeker*i collected in the coast of Miyagi prefecture, Japan.

### Files and variables

#### File: Data\_Hosono\_et\_al..csv

**Description:** Squid data ...

生物的形态学特征与其生态特性紧密关联，并适应其生存环境。作为头足类（cephalopods）的附肢，腕足与触手的形态不仅在不同物种间存在显著差异，在同一物种内也随生态习性变化而呈现丰富变异，但其同性别个体间的形态变异仍未被探明。日本枪乌贼（Heterololigo bleekeri）的雄性个体按体型分为不同类别，采取替代繁殖策略（alternative reproductive tactics, ARTs）：体型较大的“护卫型雄性”以雄性平行体位与雌性交配，而体型较小的“偷袭型雄性”则以头对头体位与雌性交配。这类替代繁殖策略会导致基于体型的交配体位与捕食策略产生差异，由此提出假说：日本枪乌贼的替代繁殖策略可能与其腕足形态的同性别个体间变异相关。本研究通过分析2021–20……年12月至次年5月两个产卵季于日本宫城县沿岸采集的枪乌贼样本的胃含物、腕足长度以及各腕足吸盘数量，对该假说进行了验证。
# 日本枪乌贼替代繁殖策略相关的腕足形态同性别变异
https://doi.org/10.5061/dryad.0000000c7

## 数据集与文件结构说明
本研究对繁殖季内采集的日本枪乌贼（Heterololigo bleekeri）的护卫型雄性、偷袭型雄性、未成熟雄性、成熟雌性与未成熟雌性的腕足与触手长度、各腕足吸盘数量以及胃含物进行了分析。结果显示，偷袭型雄性的第I-IV腕足长度显著长于其他组别个体。
本数据集为CSV格式，包含于日本宫城县沿岸采集的日本枪乌贼（Heterololigo bleekeri）的如下信息：样本ID、胴长、繁殖状态、胃含物、捕获日期、捕捞渔具、冻融处理流程、右侧第I-IV腕足长度、左侧第IV腕足长度以及右侧第I-IV腕足的吸盘数量。

### 文件与变量
#### 文件：Data_Hosono_et_al..csv
**描述：** 乌贼数据……